i rescheduled
I am in the same boat, trying to buy time to get married before GC approval, my FP are scheduled for july 8th, i rescheduled by mailing reschedule request to the local office in San Jose. I called the INS number and they said, it should be no problem. One of my friends had FP apptmt on the same day and I had asked him to make sure that I was ok. He mentioned that I was out of town and had rescheduled my FP and if it was ok, the officer at the local office said it is no problem. I will get a notice for new aptmt in a few weeks. Hope this helps, good luck!
PS. These are facts, not expert advise.