Geneva 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 Geneva.
Schedule calls for 12:00 PM to 6:00 PM in Karachi — your colleagues in Geneva will be online from 8:00 AM to 2:00 PM. With 6 hours of daily overlap, these two cities are an easy pairing; almost any reasonable hour works. These times hold for most of the year, but Geneva's daylight saving (which Karachi doesn't use) shifts them by an hour twice annually.