Welcome to the JAL forum and FT,
amerikkujin!
While I don't keep track of when business class award seats open up on SFO-HND route myself, I am pretty sure more awards will be open up in the future unless you are planning to travel during the peak of the peak seasons or blackout dates. SFO isn't a route that's particularly performing well anyway. Just keep checking I guess
Or maybe others who have experience redeeming SFO award this far in advance can chime in