Istanbul is 2.75 hours behind Kathmandu
Best overlap: 10:45 AM to 6:45 PM in Kathmandu is 8:00 AM to 4:00 PM in Istanbul.
If you set up a recurring sync, 10:45 AM to 6:45 PM in Kathmandu (8:00 AM to 4:00 PM in Istanbul) is the natural home for it. Istanbul is 2.75 hours behind Kathmandu, but the generous 8-hour window means both teams can meet well within their normal day.