How do I make formulas effective only starting from tomorrow in Google Sheets?

I made a Google Sheet for insulin-dependent diabetics, to calculate insulin units based on their meal content and glucose reading inputs. Each day has its own block of cells for the patient. When I edit the governing formulas in another sheet called 'factors', how do I make them effective starting from tomorrow, leaving previously calculated cells unchanged, to get back to as a history?

Here is the formula I'm using in a C5 calculating cell:

=if(C4="","",(C4-factors!C$7)/factors!C$5+C3/factors!C$3)

And Here is an example of the sheet.