Clearing Customs at YVR
 

Couldn't get a Global Entry appointment at ORD until late August so going to do appointment when arriving at Vancouver. I'll be traveling on a Friday arriving around 1120 - will I have enough time to make a 1200 interview?

That all depends on how many flights are arriving close to your arrival, how many lanes are open and the officer who happens to be manning your lane.

On my sole trip to Vancouver a couple years ago I thought I would be out in 5 minutes because only 5 people were in front of me and I beat the crowd of several hundred that arrived at the same time in the international terminal. I wasn't registered under any Canadian trusted traveler program so I was in the regular line. But the officer manning the lane took his sweet time taking almost 5 minutes for each person. I had to tell him virtually everything about my life when it came to my turn. It just struck me as odd because in prior trips to Calgary, Toronto and Montreal, all they asked me were the usual 2 questions that took 30 seconds: why I was visiting Canada and what I did for a living.

So yeah, no easy answer to your question since a lot of variables come into play.