Start the transition during a slow period in your sales cycle — not before peak season or a major product launch. You need a window where disruption is manageable.
Run both prep centers in parallel for at least 4–6 weeks. Route new inbound shipments to the new center while the old center processes its backlog. This prevents inventory gaps while the new relationship is proven.
Provide the new prep center with a complete SKU and prep specification before the first shipment arrives. A new 3PL that learns your requirements from the first live shipment will have errors. One that has reviewed your full spec in advance will not.
Monitor the first 5–10 shipments at the new center closely. Check FNSKU accuracy, carton counts, and outbound timing before declaring the transition complete and shutting down the old center relationship.