Prague is 4 hours behind Karachi
Best overlap: 12:00 PM to 6:00 PM in Karachi is 8:00 AM to 2:00 PM in Prague.
Keep meetings inside 12:00 PM to 6:00 PM in Karachi — that maps to 8:00 AM to 2:00 PM in Prague. Despite the 4-hour difference, a 6-hour overlap keeps things simple and gives both teams breathing room. Remember that Prague shifts for daylight saving and Karachi doesn't, so recalculate the overlap after each clock change.