Ottawa is 8 hours behind Moscow
Best overlap: 4:00 PM to 6:00 PM in Moscow is 8:00 AM to 10:00 AM in Ottawa.
4:00 PM to 6:00 PM in Moscow is when Ottawa is also working, at 8:00 AM to 10:00 AM their time. Just 2 hours of shared hours means there's little margin — set 4:00 PM in Moscow (8:00 AM in Ottawa) and start promptly. Heads up: because Ottawa changes its clocks and Moscow doesn't, the difference moves by an hour twice a year. Confirm the overlap around the DST switch.