Woocommerce Delivery Time Picker for Shipping
Woocommerce Delivery Time Picker for Shipping is a WooCommerce addon that allows customers to pick date and time for delivery when shipping on checkout page. Customers are able to select date and time for shipping in an intuitive and user-friendly widget. The delivery time will be visible to site administrators when viewing the order in the admin area. It also will be sent via emails to administrators.
If you want to allow customers to select ONLY PREDEFINED time slots, then check the WooCommerce Delivery Time Slots (they are similar in every specs, except the time picker).