Cairo is 6 hours ahead of São Paulo
Best overlap: 8:00 AM to 12:00 PM in São Paulo is 2:00 PM to 6:00 PM in Cairo.
If you set up a recurring sync, 8:00 AM to 12:00 PM in São Paulo (2:00 PM to 6:00 PM in Cairo) is the natural home for it. You share roughly 4 hours a day. That's enough for regular meetings, but treat the window as prime time and guard it. Finally, Cairo observes daylight saving and São Paulo doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.