Flight Review Question for CFI's

Do they try to make it hard to understand?
My last flight review was 4/11/09. The FAR's (61.56) say; "No
person.......each pilot must have complied with the requirements of
this section since the beginning of the 24th calendar month before the
month in which that pilot acts as pilot in command".
Does that mean the last day of the 23rd month since the month I had
the FR or the end of the 24th month in which I had my FR? Or in
simple terms, I can be PIC till the end of March or April?
Thanks,
Steve