In today's practice, We will add a new field called "Delivery Date" to the shipping address form. This field will help to save the delivery date is selected by the customer. It is the delivery date that a customer want to receive their order.
https://www.youtube.com/watch?v=WzSB3FbtXYE&list=PL98CDCbI3TNvPczWSOnpaMoyxVISLVzYQ