Cashflow forecast - help needed with formula

[blue sky]

Hi, I want to be able to do a simple cashflow forecast using excel. My question is how to treat deposits, taken in say month 1 and the balance in say month 10. The month for the Balance is variable. I may well want to run the cashflow but taking the balances in month 11 or 12 rather than say month 10. Hope this makes sense! I could do this but using extensive If statements but I am thinking there has to be a better way!

 

[blue sky]

ok, maybe I need to expalin some more:
I take an order in month one for say, £1000. In the month one cash column goes a 20% deposit of £200. In the month 10 column goes the payment balance of 80%, £800.

Whilst this is very simple to do the problem comes when I want to change the spreadsheet to reflect what happens top my cashflow if the balances are not paid until, say month 12.

I would have thought it would be a fairly common problem but how to solve it?

 

[blue sky]

anyone?