Vienna is 4 hours behind Islamabad
Best overlap: 12:00 PM to 6:00 PM in Islamabad is 8:00 AM to 2:00 PM in Vienna.
Keep meetings inside 12:00 PM to 6:00 PM in Islamabad — that maps to 8:00 AM to 2:00 PM in Vienna. Because you share 6 hours of the workday, there's no need to compromise; book the time that suits the meeting, not the map. Because Vienna and Islamabad don't both observe daylight saving, plan to re-check the overlap around March and November.