Canary Calc Start time and End time(?)

Hello,

When I have data ranging from Aug to Oct,

what should I do to recalculate only from Aug to Sep?.

Calc service seems to allow me to enter start time but not 'end time' for calculation.

The use case is when I have a certain tag from Jan to Oct,

the data from May to Oct is logged with proper scale,

but older data was incorrectly scaled, which I need to recalculate.

I have a few alternatives to do this, but was wondering if there's any way I can set an end time in this case.

Thanks