Brasília is 5 hours behind Athens
Best overlap: 1:00 PM to 6:00 PM in Athens is 8:00 AM to 1:00 PM in Brasília.
Your shared working hours run 1:00 PM to 6:00 PM in Athens (8:00 AM to 1:00 PM in Brasília). Brasília is 5 hours behind Athens. That leaves about 5 hours of common time — enough for a meeting or two, so use it deliberately. Just remember Athens changes its clocks for daylight saving and Brasília doesn't, so confirm the overlap whenever the seasons turn.