Shenzhen is 7 hours ahead of Hamburg
Best overlap: 8:00 AM to 11:00 AM in Hamburg is 3:00 PM to 6:00 PM in Shenzhen.
Shoot for 8:00 AM to 11:00 AM in Hamburg; your Shenzhen colleagues will see that as 3:00 PM to 6:00 PM. Shenzhen is 7 hours ahead of Hamburg, so the practical overlap is about 3 hours — generous enough for meetings, tight enough to be worth booking ahead. Seasonal note: Hamburg uses daylight saving and Shenzhen doesn't, so double-check the times in your own months — they can move by an hour.