Oslo is 1 hour behind Moscow
Best overlap: 9:00 AM to 6:00 PM in Moscow is 8:00 AM to 5:00 PM in Oslo.
Target 9:00 AM to 6:00 PM in Moscow, which lands at 8:00 AM to 5:00 PM for the Oslo side. That's a roomy 9 hours of common time each day, so finding a slot that suits everyone is rarely a problem. Daylight saving complicates things slightly: Oslo observes it, Moscow doesn't, so the difference flexes by an hour part of the year.