When flying from Russia to Canada, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
Great question - BGN to YYZ just means Belaya Gora Airport to Toronto Pearson Intl Airport. Now you’ll know what these unique codes when you look for flights! Vancouver Intl Airport (YVR), Montreal Pierre Elliott Trudeau Intl Airport (YUL), Calgary Airport (YYC), Edmonton Airport (YEG), Ottawa Airport (YOW) are some additional IATA codes for airports related to your trip.