Opening closing balance calculation

Hi all,

I am looking for the solution to automate variance calculation based on the opening/closing balance concept.
The idea is that calculation begins from every month 0, then the logic as follows: Oh- usage + open orders= closing balance for month 0 and beginning balance for moth 1 and so on... please see example below using formula. Note there can be different products say Product B;C etc. and the same calculation required for each

Thanks in Advance

Z.