So here's your itinerary:
HKT-BKK arrives at either 5:50/8:35
BKK-XXX leaving at midnight
Assuming that you did the work, i'm guessing your 5:50/8:35 is pm, in that case on a Friday night I would choose the 5:50 to make sure there's plenty of time to grab food/drinks then go to check your baggage for the second flight.