Ottawa is 2 hours behind São Paulo
Best overlap: 10:00 AM to 6:00 PM in São Paulo is 8:00 AM to 4:00 PM in Ottawa.
Shoot for 10:00 AM to 6:00 PM in São Paulo; your Ottawa colleagues will see that as 8:00 AM to 4:00 PM. Ottawa is 2 hours behind São Paulo, but you'd hardly notice — 8 hours of shared hours makes this feel like working in neighbouring time zones. For part of the year the maths changes: Ottawa observes daylight saving, São Paulo does not, shifting the overlap by an hour.