HKG 24小时内的transit都能直接check through行李。
如果是Cathay HKG始发的话：
Hong Kong International Airport:
Kiosks open 24 hours before and close 60 minutes before departure.
In-town check-in (Hong Kong/Kowloon Airport Express):
Opens at 6am daily; check-in available from 24 hours to 90 minutes before departure.