Best overlap: 5:00 PM to 6:00 PM in Brisbane is 8:00 AM to 9:00 AM in Geneva.
The overlap falls at 5:00 PM to 6:00 PM in Brisbane, or 8:00 AM to 9:00 AM if you're in Geneva. There's roughly 1 hour to share, so keep agendas lean and meet at 5:00 PM in Brisbane (8:00 AM in Geneva) to use every minute. The window above shifts seasonally: Geneva keeps daylight saving while Brisbane ignores it.
The US to Australia gap runs 14 to 19 hours depending on the month, and someone is always in tomorrow. Exact overlap windows for every US coast, the double-DST trap, and a rotation rule that keeps it fair. -