Houston 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 Houston.
Shoot for 10:00 AM to 6:00 PM in São Paulo; your Houston colleagues will see that as 8:00 AM to 4:00 PM. Houston is 2 hours behind São Paulo, but with 8 hours of common ground you can hold morning or afternoon meetings without anyone working odd hours. For part of the year the maths changes: Houston observes daylight saving, São Paulo does not, shifting the overlap by an hour.