How Does Minimum Delivery Interval Days Work with Holidays?

If you have set minimum delivery interval days and disabled any date or marked any day as non-working day then all the disabled days and non-working days will be added to minimum delivery interval days, if you have left the option of including holiday in interval unchecked.
If you have checked the including holiday in the interval checkbox, then it will show the minimum delivery interval days including holidays.
For example, it is 3rd March today and you have set 4 delivery days and Sunday is a non-working day for you then it will add 5 days to today’s date and the available date for order delivery will be 8th March.