São Paulo is 4 hours behind Prague
Best overlap: 12:00 PM to 6:00 PM in Prague is 8:00 AM to 2:00 PM in São Paulo.
For the smoothest call, aim inside 12:00 PM to 6:00 PM in Prague, i.e. 8:00 AM to 2:00 PM in São Paulo. The overlap is wide at 6 hours, so you can protect mornings for deep work and still find plenty of meeting time. Seasonal note: Prague uses daylight saving and São Paulo doesn't, so double-check the times in your own months — they can move by an hour.