Traveling to Mongolia, stopping in Hong Kong - How do I make sure I don't miss my flight?

Howdy!

Solo female traveler. I'm heading to Mongolia for the second time, but first time solo. I've only ever been through Istanbul airport to get there, so I'm unclear on how Hong Kong does things. Obviously it's an airport like any other, but I have some other caveats.

I have a 21 hour layover, I'll land at sometime around 7-8-9, and then take off the next day at 6pm.

I've never had a layover longer than 4 hours.

My plan is to go get a female only hostel bed, sleep until 7am their time, go out for some street photography at Goldfish street and the Bird market. Then head back to the airport around 1-3.

Is that enough time?? I'm scared I'm gonna miss the plane. haha.