Again there are no exact boundaries, but to give you an example, I applied for AOS on September 26th 2002, received FP notice within 6 weeks and scheduled FP on November 14th.
Having said that, I know people who applied for AOS in June 2002, and hadn't received FP notice till March 2003. So its your call. FP is the last thing I would worry about. Take it easy and ask your friend to stop worrying about it. When it will come, it will come, there are hundred other things you need to be worried about in the AOS process and FP is definitely not on that list!
If INS requires your FP results and doesn't have it, they will issue one and send it to your friend.