Peak season preparation starts 60–90 days before your expected volume spike. Give your 3PL a volume forecast so they can staff receiving, prep, and dispatch appropriately.
The most common peak season failure is inbound freight arriving faster than the warehouse can receive it. Stagger your inbound shipments and confirm receiving windows in advance to avoid freight bottlenecks.
Review your prep specs before the rush. Errors that are manageable at regular volume become catastrophic at 5x volume. Make sure your 3PL has current specs for every SKU before peak inventory arrives.
Have a contingency plan for overflow. If your primary 3PL hits capacity, know in advance where overflow inventory goes and how the dispatch chain stays intact.