Brasília is 4 hours behind Brussels
Best overlap: 12:00 PM to 6:00 PM in Brussels is 8:00 AM to 2:00 PM in Brasília.
The overlap falls at 12:00 PM to 6:00 PM in Brussels, or 8:00 AM to 2:00 PM if you're in Brasília. The 4-hour gap barely gets in the way — you've got 6 hours of overlap, so pick whatever time fits the agenda. Just remember Brussels changes its clocks for daylight saving and Brasília doesn't, so confirm the overlap whenever the seasons turn.