Appreciate the warning, but it's already taken care of. I'm sitting in YYZ right now and just got my EOA interview in terminal 3. You have to go through the normal CBP line, but once you get to an agent you say you need your interview. They'll verify that you're provisionally accepted, then send you over. I brought a copy of my acceptance letter to expedite the process.

The security line at 9am was about an hour (yuck), but then it just took about 5 minutes to see an agent, and 15 minutes for the interview. Naturally, by the time I finished my interview, the line was almost empty.

I learned from the agent that I should have applied for Nexus. I thought Nexus was just for Canada <--> US, and I wanted it to cover other countries too. But the agent said Nexus is better when going US-->Canada because it's like Global Entry going into Canada, AND Nexus includes a free Global Entry membership. Duh. I can add Nexus for $50, but I'll have to schedule another set of interviews. Including with the Canadian border folks, and that must be scheduled in Canada. Trick is that you have to schedule that interview in advance, usually with a fairly long lead time, and I never know about my trips more than about 3 weeks in advance. So maybe eventually I'll give it a try and see if I can get an appointment with that short a notice.