For whatever reason(s), anecdotally HKG flights never see any published PZ (confirmable upgrade inventory), even wide open flights. They just clear from the waitlist at T-36 or T-24. So your strategy of issuing an award ticket and waiting for PZ to open could well backfire. I'd do the opposite: buy a coach ticket and waitlist the upgrade, and if for some reason it doesn't clear by T-24 or whatever your threshold is, then issue an award.