GCDream
If you do a search on my username you'll find the 2nd FP experience in Phoenix that I posted.
Basically, my advice is, yes you can do early FP, but go there really early in the morning (7:30am), also preferrably go there
on a Saturday because there seems to be less people.
They never questioned or gave us any trouble about early FP.
Be sure you go there with your passport as well since they asked to see the I-94 as well for my wife. If they don't ask for it, fine, but
be prepared to show it.
Once you get in, fill out the paperwork quickly (since you've already done it before on 1st FP) and you can be ahead of the line.
Hope this helps. Don't hesitate to ask if you have further questions.
Phoenix Saint.
