Istanbul is 3 hours ahead of Reykjavik
Best overlap: 8:00 AM to 3:00 PM in Reykjavik is 11:00 AM to 6:00 PM in Istanbul.
Reykjavik and Istanbul overlap from 8:00 AM to 3:00 PM (Reykjavik) to the equivalent 11:00 AM to 6:00 PM in Istanbul — that's your meeting window. You won't be short on options — 7 hours of overlap leaves space for recurring syncs and ad-hoc calls alike.