Beijing is 4.5 hours ahead of Tehran
Best overlap: 8:30 AM to 1:30 PM in Tehran is 1:00 PM to 6:00 PM in Beijing.
The sweet spot is 8:30 AM to 1:30 PM Tehran time, matching 1:00 PM to 6:00 PM in Beijing. You've got a decent 5-hour window. Set a recurring time near 8:30 AM in Tehran (1:00 PM in Beijing) and stick to it.