ATC lasts 30 minutes from engine start to loss of contact so a guesstimate would be he was airborne 10 minutes after start-up. Sochi/Adler is right on coast.
Aircraft goes into sea 1.5 km offshore. Sounds like he was returning to airport and from tone of transmissions, not in urgent trouble. We may not hear much about it, seems this was a military flight, so might not be subject to ICAO reporting rules.