Istanbul is 6 hours ahead of Brasília
Best overlap: 8:00 AM to 12:00 PM in Brasília is 2:00 PM to 6:00 PM in Istanbul.
Plan around 8:00 AM to 12:00 PM in Brasília, which is 2:00 PM to 6:00 PM in Istanbul, to catch everyone during office hours. Since Istanbul is 6 hours ahead of Brasília, the workdays overlap by around 4 hours; 8:00 AM in Brasília (2:00 PM in Istanbul) makes a reliable recurring slot.