Excel Calculation across 2 sheets, and freesing at end of month

Please hang in there while I ATTEMPT to explain what I'm trying to achieve. I'll do this as simple as possible. On sheet one column C there is a check mark placed upon completion of a project. C46 calculates the percentage of work done depending upon the amount of check marks placed in C1-C45, this works fine. Sheet two row 3 are the months of the year, B3=Sept, C3=Oct, D3=Nov etc etc. I need sheet 1 C46 to populate in sheet 2 B4 until the end of the month and then freeze, At this point we're in the next month ( C5 ) and C46 should now start populating C5, and so on through the months of the year. The goal here is to  check off finished work on sheet 1 as it is completed with the percentage ( C46 ) populating in the current month on sheet 2, at the end of the month sheet two freezes the percentage for that month, and C46 then begins calculating the remaining check marks if any in the following month on sheet 2.


 I am a novice at best with Excel so please excuse me if I'm unclear or missing needed information, please ask questions, I'll be happy to try and clarify, this is an extremely important project to me. Thanks again.

Oh and BTW Excel 2010 from Office ProPlus 2010