Electric company read date changes, what to use billing date

Say, looking at my electric bill, seems it was read 12/09 and 11/11 . Not sure where i saw it but i recall my meter can be read in a window of several days. I’m guessing that doesn’t work well with the monthly electricity tracking ?? or what would I want to enter for a billing date ??
thanks much for your time.

Unfortunately, Sense only allows a single billing date for the Trend summary under Bill. Under Bill, you can only view the summary from a day in one month up to the same day in the next month (i.e. June 6th to July 5th, inclusive). I have a smart meter, but even with that, the length and start days of my billing period vary by up to six days.

What I do, is I set my Sense billing date to start on the median day, the 20th. Occasionally I will readjust it when I want to compare to a specific bill, but then I change it back to the 20th.