Delivery Wait Times can be set up under the Order Type for a standard wait time. When a delivery zone is set up you do not have to enter an additional wait time unless you have multiple delivery zones that will need additional wait time.
The Additional Wait Time will be in addition to the Wait Time set up under the Delivery - Order Type.
In the example below there is a Standard Wait time set to 30 minutes. On Zone 1 deliveries there is no additional. For Zone 2 there is an additional wait time of 10 minutes that is in addition to the Standard Wait time of 30 minutes making the total Wait Time for Zone 2 - 40 minutes.