Finance help ( possible dynamic ranges)

[golfedrocks]

hello i am currently doing a cash budget spread sheet for my uni work , all of it ive done fine. It has to be done in a way where you have one page for data entry and then the other sheets will alter themselves with no data.

The problem i am stuck with is some of the customers take a few months to pay , so the information goes a few months down the line , which to do it for a set 2 months is easy. But we have to do it in a way that we can alter how many months they take to pay and it will adjust all the information ?

does anyone know how i can get around this problem ?

thanks