I have only once upgraded at check-in which was J to f and only becasue it was my Birthday and on the DXB-LAX route- so thought it would be worth it!!

If I was a blue or even silver I would probably do it in advance, but I lik eto play the odds-- no matter how bad they really are in this case!!

I plan to wait till on board to upgrade on my next trip to YYZ-- loads look full, so hoping for the op-up, and if that fails that there is still space in J and do it on board.