I'm also on my AP build and , though I have looked at a number of pics, the answer isn't as clear as I would have thought. I've ended up leaving a little return edge both in and out. On the AP, the outer inferior bicep mold doesn't allow for much return. There just isn't much plastic there.
Anyhow, I moved on. I am worried that my biceps are too snug though. I'm even more worried about my 9 year old's fit.