Function to order fulfillment

Hello,

Could you please help me creating a function where I can input three variables - 1) the necessity to be produced, 2) the prodution plan dates, 3) the production quantities, and the function returns me the date when the entire necessity is fulfilled?

In the attached file, the doubt is better explained.

I know how to do it by formula, but I really need a code with a function in this case.

Thanks in advance!

Up.
Any helps here please?

Thanks!