Whe i spoke to the USCIS rep for a "Biometrics" appointment, she said I would have to take a separate "INFOPASS" appointment for PP stamping. You may request the ASC office to stamp your PP at the time of Biometrics.
If your biometrics were already taken earlier, iguess you can just take an "INFOPASS" appointment to get your PP stamped.The Biometrics appointment is for info like FP,phots..required for the GC Card.
I-140/I-485 RD: Sept 20,2002
I-140 AD: Dec 2002
FP:Sept 2004
I-485 AD: 30 Sept,2005,,Schedules for Biometric appoinment