Johannesburg is 8 hours behind Melbourne
Best overlap: 4:00 PM to 6:00 PM in Melbourne is 8:00 AM to 10:00 AM in Johannesburg.
If you set up a recurring sync, 4:00 PM to 6:00 PM in Melbourne (8:00 AM to 10:00 AM in Johannesburg) is the natural home for it. Since Johannesburg is 8 hours behind Melbourne, the overlap is narrow (about 2 hours); a single, well-protected slot beats hunting for time each week. Keep an eye on the calendar — Melbourne observes daylight saving and Johannesburg doesn't, which nudges this window by an hour twice a year.