This is particuarly a problem with longhaul flights on CX.

You are lucky to find 1 A seat on the days you checked. On many days I checked, CX830/830 showed A0 several months out. CX889/889 tend to have better availability in A. That said, CX is pretty good at releasing A seats closer to departure. You could book one A seat first, then wait for them to release another one later. Or you could wait until close to departure to book, although it could be as close as a few days prior.