Same-day fulfillment requires the following to all be true: inbound inventory arrives before the carrier cutoff, prep specs are pre-confirmed and labels are ready, order details are submitted before warehouse processing begins, and the prep complexity is within same-day scope.
The biggest bottleneck in same-day fulfillment is usually the prep step, not the shipping step. A 3PL that can receive, prep, and stage 500 units in four hours can execute same-day. One that needs 24–48 hours for receiving alone cannot.
Port-access 3PLs have a structural advantage for same-day. Container freight that arrives at Port Everglades at 8am can be at a Broward warehouse by 10am, prepped by 1pm, and picked up by a carrier at 3pm for same-day dispatch.
Confirm same-day capability with specific conditions before relying on it for time-sensitive orders. A blanket 'same-day dispatch' claim from a 3PL without specific conditions attached is a marketing claim, not an operational one.