I'm not sure how accurate the lounge's opening times listed on the website are. I remember being worried I wouldn't get to spend much time there. I used the lounge last month before the flight to JFK and it opened well before 2130. If I'm not mistaken, I entered around 2030 and there were already a handful in the J lounge (no one in the F lounge when I entered). It was a great lounge.

YVR is a beautiful airport in my opinion, but my one complaint with the "natural" lighting in the seating area in front of the food concessions in the non-US international area (the one place with tables) is that it gets too dark to read or do much work by early evening.