I have a flight in First coming up in November from LAS-DCA (A319). Right now, the Mrs and I can't get seats together. The only 2 seats available were back to back window seats (2 & 3F). It appears that 1A&C are both blocked according to the seat map on ExpertFlyer. When do they typically unblock those seats? Are they only assignable on the day of travel? ExpertFlyer is still showing F2, so it looks like they are still selling a couple of seats in F. Thanks!