Just went through a few useful posts here about F availability, but still not sure about 1 thing.

I have 2 reward tickets booked in business, and really want to cancel them and switch to reward F. Current availability as per SeatSpy, RewardFlightFinder and BA itself (book with Avios) show only 1F available for that date.
I was wondering if BA follows the old LH model where they open more F slots as the travel date gets closer.

For reference, this is from BOS -> LHR. I've setup alerts for any 2F openings in the surrounding areas (NYC, PHL, even ORD) for my travel date, but still wanted to check here in case someone knows of any upcoming major announcements or changes.

Thanks in advance, and safe travels!