Adding a delivery time to your store gives your customers an idea of when they can expect to receive their order from your store.
This is shown on your site's footer section. By default, 3-5 days are selected.
If you wish to change this, navigate to the My account settings section by clicking the dropdown on the top right.
Select the Store details section on the left and scroll to the Additional information section.
Here, you will see the option for Delivery happens within. On clicking it, a pop-up opens where you can choose your default delivery time. You can also choose to add a custom delivery time.
Once selected, click on Save to update your delivery time.