Houston is 15 hours behind Melbourne
Best overlap: 8:00 AM to 9:00 AM in Melbourne is 5:00 PM to 6:00 PM in Houston.
For the smoothest call, aim inside 8:00 AM to 9:00 AM in Melbourne, i.e. 5:00 PM to 6:00 PM in Houston. Houston is 15 hours behind Melbourne. That's only 1 hour of overlap, so pair live calls with async follow-ups to make the most of it. Because of the gap, Houston is already on the previous day, so confirm you're both talking about the same calendar date.