Moving inventory to a third-party logistics provider is easier when the warehouse, your sales channels, and your team agree on the details before the first shipment arrives. A connection that imports orders is only one part of the job: the products, stock quantities, shipping instructions, and exception process must agree too.
This 3PL onboarding checklist explains what to prepare before starting ecommerce or B2B fulfillment. It is useful whether you sell through Shopify, Amazon, Walmart, wholesale purchase orders, or a combination of channels.
What should you prepare before sending inventory to a 3PL?
Start with a clean SKU file, an inbound inventory plan, a written integration scope, packing and shipping instructions, named support contacts, and completed test orders. Confirm which inventory is ready to sell before releasing customer orders.
- Your products: SKUs, variants, barcodes, dimensions, weights, and handling requirements.
- Your inbound shipment: expected quantities, carton or pallet details, delivery timing, and receiving documents.
- Your systems: sales channels, account permissions, SKU mappings, and the data that must move between systems.
- Your orders: packaging, carrier accounts, service levels, retailer requirements, and returns instructions.
- Your launch: test results, inventory reconciliation, support contacts, and approval to start shipping.
1. Agree on the work the warehouse will perform
Describe the operation in units the fulfillment team can use: individual items, cases, pallets, or orders with several parcels. Share your typical items per order, sales channels, anticipated volume, and any seasonal peaks. Separate direct-to-consumer packing from retailer or marketplace preparation; they can require different labels, documents, and handling.
Record any kitting, inserts, custom packaging, inspection, lot or serial tracking, and returns work in the service scope. Confirm applicable fees and terms before launch. A task that seems small to your business can change the warehouse workflow when it applies to every order.
2. Build one reliable product and SKU file
Give every sellable variant an identifiable warehouse SKU and record how it maps to each channel. Include the product description, barcode, unit of measure, case quantity, product dimensions and weight, and any agreed handling details. Keep unit measurements separate from carton and packed-shipment measurements.
For example, a single bottle and a case of six bottles need an explicit unit conversion. If a bundle contains two different products, record the component SKUs and quantities. Do not leave the warehouse to infer the contents from the bundle name.
Where possible, use consistent SKUs across systems. If channel identifiers differ, agree on a mapping rather than changing identifiers during launch. Shopify’s SKU guidance explains why missing, duplicate, or mismatched SKUs can affect inventory tracking and third-party connections.
3. Define the integration beyond the platform logo
For each storefront or marketplace, name the connection method and the person responsible for setup. It may use an existing connector, an integration partner, an approved app, or scoped custom development. Confirm the account permissions and available interfaces before setting a launch date.
- Orders: Which orders import, when they are released, and how duplicates are prevented.
- Inventory: Which system controls sellable stock, which location supplies it, and how updates and reserved quantities are handled.
- Fulfillment: How shipping methods, labels, carrier accounts, and tracking updates map between systems.
- Exceptions: What happens to cancellations, partial shipments, invalid addresses, and connection errors.
Use the platform’s authorized connection process and agree on the access required. A successful login does not prove the operational flows are working. Walmart’s Marketplace integration documentation, for example, describes inventory, orders, shipping, and returns as distinct functions. Confirm which functions are included in your own connection.
4. Plan the inbound receipt and inventory handoff
Before delivery, provide expected SKU quantities, carton or pallet information, relevant packing lists, and the agreed receiving reference. Confirm how the warehouse wants products and cartons identified, how delivery appointments are arranged, and how shortages, overages, or damaged goods will be reported.
For a warehouse transition, reconcile stock at the old location and record what is in transit. Agree when each system will stop or start advertising that inventory as available. Sending the same stock quantity from two locations can create an overselling risk if the systems count it twice.
Treat arrival, receiving, and availability for fulfillment as separate checkpoints. Agree who confirms the received quantities and who authorizes release of the first customer orders.
5. Document packaging, carrier accounts, and shipping rules
Specify the package type, protective materials, inserts, packing slips, and any retailer-provided labels or routing instructions. Provide accurate weights and dimensions for the relevant products and packages so the team can prepare labels and compare appropriate shipping options.
Confirm whether shipments use your carrier account, the fulfillment provider’s account, or labels supplied by a customer or retailer. Map vague checkout labels such as “Standard” to the agreed carrier service or selection rule. Decide who approves an alternative if the preferred service is unavailable.
Record the order cutoff, local timezone, operating days, and requirements for any same-day processing commitment. Keep processing commitments separate from carrier delivery estimates. International documentation, duties arrangements, and special handling should be scoped where relevant.
6. Set returns instructions and name the people responsible
Agree how returns are identified, checked against an authorization, inspected, and placed into the appropriate inventory status. Define who can approve restocking, disposal, or another disposition. Returned stock should not automatically become sellable simply because a parcel reaches the warehouse.
Name an operational contact and an account contact on both sides. Record the communication channel and escalation route for receiving discrepancies, urgent order questions, and technology failures. This makes an exception easier to resolve than relying on a general inbox with no agreed owner.
7. Test the complete order journey
Run an agreed pilot before releasing the full order flow. Use authorized test methods or controlled orders so testing does not accidentally create a live customer shipment. Record the order identifier, expected result, actual result, and any correction needed.
| Test | What to confirm |
|---|---|
| Single-item order | The correct SKU, quantity, address, and shipping instruction reach the warehouse. |
| Case or bundle | The agreed unit conversion or component quantities are used. |
| Low stock or unavailable item | Inventory availability and the exception process behave as agreed. |
| Cancellation or order change | The team knows when a change can be accepted and what happens after work begins. |
| Shipment and tracking | The shipment confirmation, carrier, and tracking information return to the correct channel. |
| Return | The return reference, inventory status, and disposition follow the approved instructions. |
A pilot is complete when the agreed results are verified and unresolved issues have an owner. Keep the launch checklist with the operating instructions so it remains useful when products, channels, or packaging change.
How FlexHub approaches fulfillment onboarding
FlexHub provides warehousing, fulfillment, and active retail distribution from Paterson, New Jersey. Onboarding discussions cover your products, inbound inventory, sales channels, shipping profile, and the services your account needs. Explore FlexHub’s services and bring any retailer or marketplace requirements into that conversation.
The support model includes a dedicated Account Manager and direct access to warehouse leadership through WhatsApp. Agree which person handles commercial questions, operational exceptions, and integration work for your account.
FlexHub is also developing a proprietary WMS. Existing integration options and planned native connections are different stages of the technology offering. Confirm the current connection method, required data flows, permissions, and any development scope for your platform during onboarding.
Questions to ask before your first shipment
How long does 3PL onboarding take? There is no single timeline for every account. Product data, inbound readiness, connection complexity, packaging, retailer requirements, and successful testing all affect the launch date. Ask for milestones and responsibilities for your account.
Do all channels need identical SKUs? Consistent identifiers simplify the work, but different channel identifiers can be mapped to an agreed warehouse SKU. Verify the mapping for variants, cases, and bundles before launch.
What if my platform is not in an integration directory? Ask whether an existing partner connection or custom integration can support the required workflow. Confirm available APIs or data interfaces, permissions, responsibilities, cost, and testing before assuming the connection is ready.
Preparing to move your fulfillment?
Share your SKU list, sales channels, order profile, inbound plans, and shipping requirements with the team. Request a fulfillment quote from FlexHub and use this checklist to make the first conversation more specific.
This guide draws on FlexHub’s documented operating workflows and the linked platform documentation. Account requirements, service availability, and integration scope are confirmed during onboarding.