Customer Delivery Tracking

I'd like to know how to create a spreadsheet that has all my customers listed. I want to keep track of their deliveries and have it show me when they'll need another delivery. I don't know where to get started. The best example I can give is this...

Customer A - needs to have an order every week.
Customer B - needs to have an order every 2 weeks.
Customer C - needs to have an order every 3 weeks.
All 3 customers may or maynot be delivered on the same truck that goes out every week. Obviously, some weeks only Customer A goes and some weeks all 3 customers may go.

I want to open up Excel daily and see who needs an order. Where do I start with this?

The core of what you are doing is, determining the next ship date, and comparing it to TODAY(), right?

Anyway try on the attached for size.