Brasília is 3 hours behind Reykjavik
Best overlap: 11:00 AM to 6:00 PM in Reykjavik is 8:00 AM to 3:00 PM in Brasília.
Plan around 11:00 AM to 6:00 PM in Reykjavik, which is 8:00 AM to 3:00 PM in Brasília, to catch everyone during office hours. That's a roomy 7 hours of common time each day, so finding a slot that suits everyone is rarely a problem.