Tehran is 7.5 hours ahead of Montreal
Best overlap: 8:00 AM to 11:00 AM in Montreal is 3:30 PM to 6:30 PM in Tehran.
The sweet spot is 8:00 AM to 11:00 AM Montreal time, matching 3:30 PM to 6:30 PM in Tehran. You've got a decent 3-hour window. Set a recurring time near 8:00 AM in Montreal (3:30 PM in Tehran) and stick to it. Just remember Montreal changes its clocks for daylight saving and Tehran doesn't, so confirm the overlap whenever the seasons turn.