Bucharest is 2 hours ahead of Reykjavik
Best overlap: 8:00 AM to 4:00 PM in Reykjavik is 10:00 AM to 6:00 PM in Bucharest.
Book within 8:00 AM to 4:00 PM Reykjavik time (10:00 AM to 6:00 PM in Bucharest) and both teams will be at work. That's a roomy 8 hours of common time each day, so finding a slot that suits everyone is rarely a problem. Daylight saving complicates things slightly: Bucharest observes it, Reykjavik doesn't, so the difference flexes by an hour part of the year.