Ticket Sales RSUM days prior to close

Hi there,

I'm getting asked by marketing for a season comparison Days Prior to close (or open).  I've got Days after onsale set up with 1st MOS as the start but during the season sales velocity is hard to compare.  Sales prior to performance also gives a skewed view for predictions.  Are there any thoughts on a way to measure cumulative sales relative to an in-season event like open or close.

Cheers,

Heath