Calgary is 12 hours behind Dhaka

There is no standard 8-to-6 overlap. Someone joins early or late.

Given Calgary is 12 hours behind Dhaka, 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 Dhaka or the first hour for Calgary is usually the least painful option. Just remember Calgary changes its clocks for daylight saving and Dhaka doesn't, so confirm the overlap whenever the seasons turn.