Formula/Method to display weekdays between 2 listed weekdays for a general weekday order schedule

Trying to find an easy way to calculate auto-orders between final order days for a delivery.

For example 1 of my vendors may send deliveries on Mon/Wed/Friday, but their final "drop" date that sends those orders may not be the same as another vendor on the same delivery schedule.

Example:

Monday delivery drops final order on Thursday

Wed del drops orders on Saturday

Fri del drops Tues

Working backwards from the "drop" day fills in each nights auto-order included in each delivery. Would there be a way to have Excel fill in that the days between in parenthesis:

-Tuesdays drop (previous drop is Saturday, days between is Sunday, Monday and includes orders from those days as well) delivers on Friday

-Saturdays drop (previous drop is Thursday; days between Friday) delivered on Wed

-Thursdays drop (previous is Tuesday; days between Wednesday) delivered on Monday

Open to other ways, but it would be a huge help to automate this calculation of the weekdays between between vendors instead of just doing each change in my head and typing it in.