Madrid 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 Madrid.
Aim for 8:00 AM to 5:00 PM Reykjavik time — that's 9:00 AM to 6:00 PM over in Madrid. Despite the 1-hour difference, a 9-hour overlap keeps things simple and gives both teams breathing room. Remember that Madrid shifts for daylight saving and Reykjavik doesn't, so recalculate the overlap after each clock change.