search the message boards. there are tons of them.
Besides, it's no biggie. Standard procedure. Reach early, stand in line (not standard but the line for appointments even though you don't have a specific one). Go to room assigned, hand over approval notice, wait......., get finger printed and sign for i-89, wait.....................................(ibis check in progress, I guess!!!)...................................................................................................................................................................get called for stamp, hand over passport, get stamp and walk out.
I got it stamped in NY but have friends who got it stamped in NJ and we all had the same experience.
best of luck.