Brussels 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 Brussels.
Keep meetings inside 8:00 AM to 5:00 PM in Reykjavik — that maps to 9:00 AM to 6:00 PM in Brussels. Brussels is 1 hour ahead of Reykjavik, but you still share a generous 9 hours of overlap, so scheduling is easy and there's room to move a meeting when you need to. These times hold for most of the year, but Brussels's daylight saving (which Reykjavik doesn't use) shifts them by an hour twice annually.