The estimated date is calculated by adding the Shipping Days and the Return Days to the date when the order was shipped.

For example: 

If your order was shipped on 10 October 2021, and it takes 3 days for the shipment to arrive, plus the customer has 15 days to return the item, then the estimated date would be 10 October 2021 + 3 days + 15 days = 28 October 2021.

You can configure the Shipping Days and Return Days on your AppScenic Account.