Will you have checked bags? If so (and your first airline won't through-check them), then you'll have to wait until approx 3 hours before your flight to check them in with QR. Your other option would be to go into town and drop your bags at the Airport Express check-in desk (last time I was there it was open for QR pax from 13:35).

If no checked bags (or they are checked through), then just approach the transit desk airside for your onward boarding pass and stay airside.

no checked bags!

this is great advice, thank you kindly. I’ll report back with results!

thanks again for the reply!

FYI, transfer counter opens at E1 at 2pm for the 18:50 departure. I was actually able to get a mobile boarding pass so didn’t need to wait for it to open, which worked out just fine. FYI, you can use any of the cx lounge but you can’t use the plaza premium first class lounge until 3 hours prior to departure. We still had to go to the gate and get our passports scanned before we could board and have them issue us boarding passes again so make sure you plan for this.

we didn’t have checked bags of course.

A mobile boarding pass...??...I didn't think QR did that at HKG? Is this some new magic? :)

Did you have bags to check in or was that just for getting your BP with hand luggage only?

Have the same query for tomorrow, aiming to check-in physically (downtown check-in doesn't suit us due to location for this trip) when QR817 opens (departure 18:50 31/12), but flying out on QR815 (departure 00:50 1/1).

Good way to see in the New Year, shame it's one of their old bunky 777's on the route even though we had one with Q suites on the way over!

You posted last month but yes you can use a mobile boarding pass. They'll make you change it at the gate for a paper one though.

Looking a few times at the queue waiting for the outside security check, I would say that over 90% of pax use a mobile boarding pass. I am one of the old guy printing a BP just in case.
You have no problem going to the gate with a QR mobile pass but, as mentioned above, they will print a hard one at the gate.

To provide a data point..... arrived at 15:45, check-in was already open. No problem with checking in and checking in bags also for QR815 departing 1/1 00:50.