I would absolutely positively get an earlier flight into YVR. I was connecting off AS (QX actually) to BA 84 a couple of months ago, and started with 3 hours for the connection. Various bad things happened and my QX flight didn't arrive until 20:05. I discovered that the transit kiosk in the YVR arrivals hall shuts at 8 PM (watched the immigration officers walk away laughing) so I had to wait in the 500+ people queue (mainly those who had arrived on BA 85) to go landside, up the stairs, past the (empty) BA counter, through security, and sprinted through the concourse; and made the flight only because the aircraft had landed 40 min. late. I was the last person to board before they closed the doors - after the standbys.
(However 62A was still waiting for me
)
Don't risk that short a connection. Go early and enjoy the BA and CX (if open) lounges.