Amazon provides the estimated delivery time to buyers on the offer listing and checkout pages. We base this estimate on the time between when the buyer places an order until the order is delivered to the buyer's address.
Total Delivery Time = Handling Time + Transit Time (+ any holidays)
Handling time: The time elapsed between when the buyer places the order and when you hand the order over to the delivery service.
There are two ways you can modify the handling time:
Transit time: The time between when you hand the order over to your carrier until its delivery to the buyer's address. You can modify the transit times for your SKUs by editing your shipping templates.