Current situation: I am booked YYC-YVR-LHR on a latitude flight pass and upgrades for both legs are already confirmed. I'm booked on the earliest YYC-YVR leg I could get with the flight pass, which arrives YVR at 15:40, with the YVR-LHR leg departing 18:30.

What I want: to leave YYC early enough to spend part of the day in Vancouver, but obviously without disturbing the YVR-LHR leg or the upgrade I already have confirmed.

Question: any experience out there in standing by early on a 2-leg FP booking like this? If I wanted to get out of YYC at say 9 am or so am I pipe-dreaming? Is there any chance that in standing by on the first leg I could frig up the u/g on the second leg?

Thanks!