Most efficient way would be to run a Google Search with YYZ and YUL as origin, and BOG as destination, non-stop, searching for Premium Economy fares. Then, click the date and it'll show you which dates that's offered.

The point here isn't to buy a PE fare, but that search will filter out any aircraft without a PE cabin, and on this route that should cut out everything except AC widebodies.

Keep in mind that this far in advance, equipment changes are absolutely possible.