Copenhagen is 1 hour ahead of Reykjavik
Best overlap: 8:00 AM to 5:00 PM in Reykjavik is 9:00 AM to 6:00 PM in Copenhagen.
Both offices are open during 8:00 AM to 5:00 PM Reykjavik time, which is 9:00 AM to 6:00 PM in Copenhagen. Copenhagen is 1 hour ahead of Reykjavik, and with 9 hours of overlap you can even run back-to-back calls without stepping outside business hours. Just remember Copenhagen changes its clocks for daylight saving and Reykjavik doesn't, so confirm the overlap whenever the seasons turn.