There is no standard 8-to-6 overlap. Someone joins early or late.
Given Perth is 14 hours ahead of Calgary, the realistic answer is that there's no convenient shared slot during normal business hours. Catch the edges of the day: the last hour for Perth or the first hour for Calgary is usually the least painful option. Heads up: because Calgary changes its clocks and Perth doesn't, the difference moves by an hour twice a year. Confirm the overlap around the DST switch.
| Local time | 12am | 1am | 2am | 3am | 4am | 5am | 6am | 7am | 8am | 9am | 10am | 11am | 12pm | 1pm | 2pm | 3pm | 4pm | 5pm | 6pm | 7pm | 8pm | 9pm | 10pm | 11pm |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Calgary America/Edmonton | ||||||||||||||||||||||||
Perth Australia/Perth |
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. -