I hope I can explain myself clearly!!

I am setting up a worksheet to enable the construction of a cash flow chart
relating to property development. I have an input section where I can select
the month in which an activity will commence, how long it will run for and
when it will end. I can also select the months in which payments should be
made, as a percentage of the total payments.

For example, I might input that the construction stage commences in month 3
and run for 10 months. I am struggling to get my mind around how to set up
worksheet so that the relevant costs for construction are shown in the cash
flow as commencing in month 3 and as continuing for 10 months.

I also wish to show costs as being apportioned at stages along the 10 month
period again as per data entered into input section.

I really hope this makes sense. Can anybody give me any advice as to how I
might be able to link the input data with the Cash Flow as per my rough
explanation above?

Many thanks.