Hong Kong is 7 hours ahead of Copenhagen
Best overlap: 8:00 AM to 11:00 AM in Copenhagen is 3:00 PM to 6:00 PM in Hong Kong.
Your shared working hours run 8:00 AM to 11:00 AM in Copenhagen (3:00 PM to 6:00 PM in Hong Kong). You've got a decent 3-hour window. Set a recurring time near 8:00 AM in Copenhagen (3:00 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.