Might be a bit different from straight Aeropoint, I had my 2016 summer (early to mid August, round trip YYZ - NRT) ticket booked thru United Milage plus on a AC metal. And the seats were released from Air Canada to Mileage plus in March of the same year.
I am checking everyday now for our summer one way ticket on Air Canada metal as we speak. AC gives us the best schedule for out connection.