Apologies is this has been answered before. I couldn’t find the information.
My WDW trip begins on April 23. There are 29 days in February. Can I book fast passes on February 22, or must I wait until February 23?
Actually 60 days, not two months.
I have a spreadsheet with dates, and then I use a formula that sets it equal to the cell with the date minus 60 (or 30, etc). It then gives me the date to schedule Fastpasses.
Feb 23rd edited to correct! Oops.
60 days is exactly that, as is 180:days for ADRs.
I might have waited a day longer than necessary if not for you folks. Thanks so much for the information!
Actually, I think it’s the 23rd!! 
I think you are correct. It is the 23rd. Once I did the math in a spreadsheet, that became clear.