You claim it in HKG (AC checks it to HKG), and recheck your luggage in the morning. I just did it two days ago. In HKG, there is no transit hotel in the air side, and likely you need to clear the custom and immigration staying in Regal Airport Hotel (my routine), so I doubt AC allows you to leave the checked bags inside the airport and get loaded to the connecting flight, in case you do not fly in the morning.