Best overlap: 8:30 AM to 12:30 PM in Edinburgh is 2:00 PM to 6:00 PM in Delhi.
8:30 AM to 12:30 PM in Edinburgh is when Delhi is also working, at 2:00 PM to 6:00 PM their time. You've got a decent 4-hour window. Set a recurring time near 8:30 AM in Edinburgh (2:00 PM in Delhi) and stick to it. Because only Edinburgh changes its clocks, the overlap above isn't fixed; expect a one-hour shift when Edinburgh enters or leaves daylight saving.
London to New York is five hours apart, except for the five weeks a year when it isn't. Exact overlap windows for every US zone, the 2026 DST mismatch dates, and where to put the recurring sync. -