Hong Kong is 6 hours ahead of Copenhagen
Best overlap: 8:00 AM to 12:00 PM in Copenhagen is 2:00 PM to 6:00 PM in Hong Kong.
Your shared working hours run 8:00 AM to 12:00 PM in Copenhagen (2:00 PM to 6:00 PM in Hong Kong). You've got a decent 4-hour window. Set a recurring time near 8:00 AM in Copenhagen (2:00 PM in Hong Kong) and stick to it. Because only Copenhagen changes its clocks, the overlap above isn't fixed; expect a one-hour shift when Copenhagen enters or leaves daylight saving.