Your call on whether or not to play seat roulette, but I'd probably stay where I am. Most TATL flights are likely to go out pretty full at this time of year regardless of the seat map, so moving yourself to a currently empty row might not count for much at departure time. If you're happy in 19F, stick with it. But maybe monitor things a few hours after online check-in opens...if plenty of rows continue to remain open, I might consider switching at that point.