Dallas wrote
c. Except as provided in paragraphs (d), (e), and (g) of this
section, no person may act as pilot in command of an aircraft unless,
since the beginning of the 24th calendar month before the month in
which that pilot acts as pilot in command, that person has --

I've been assuming that the BFR had to be accomplished like the FAA
usual "last day of the month". i.e. Last BFR December 12, 2007 -
Next BFR before December 31, 2009?

Yep...that's what paragraph (c.) says. If the Flight Review (not BFR)
takes place on any day in Dec 2007, you're good to go throughout Dec
2009.

Bob Moore
ATP
Flight Instructor ASE-IA