Geneva is 7 hours behind Beijing
Best overlap: 3:00 PM to 6:00 PM in Beijing is 8:00 AM to 11:00 AM in Geneva.
The overlap falls at 3:00 PM to 6:00 PM in Beijing, or 8:00 AM to 11:00 AM if you're in Geneva. Roughly 3 hours of common time means scheduling is manageable; just avoid the very edges of the window. The window above shifts seasonally: Geneva keeps daylight saving while Beijing ignores it.