Islamabad is 4 hours ahead of Vienna
Best overlap: 8:00 AM to 2:00 PM in Vienna is 12:00 PM to 6:00 PM in Islamabad.
Book within 8:00 AM to 2:00 PM Vienna time (12:00 PM to 6:00 PM in Islamabad) and both teams will be at work. Islamabad is 4 hours ahead of Vienna, but you'd hardly notice — 6 hours of shared hours makes this feel like working in neighbouring time zones. Note that Vienna follows daylight saving while Islamabad stays put, so the times above drift by an hour seasonally.