Istanbul is 2 hours ahead of Hamburg
Best overlap: 8:00 AM to 4:00 PM in Hamburg is 10:00 AM to 6:00 PM in Istanbul.
The sweet spot is 8:00 AM to 4:00 PM Hamburg time, matching 10:00 AM to 6:00 PM in Istanbul. Scheduling is forgiving here: with 8 hours of overlap, a missed slot just means picking another one the same day. Just remember Hamburg changes its clocks for daylight saving and Istanbul doesn't, so confirm the overlap whenever the seasons turn.