I think it depends on the FP center
Our scheduled FP date is 03/06 - Wednesday. Both of us work out of town during weekeys so we went to the FP center on 02/09 to reschedule it for a Saturday. We were told that we can do FP on any Wednesday or Saturday within 2 months AFTER the scheduled FP date but not prior to it. So now we\'ll go on March 9th.
We did not have any proof stating we\'ll be out-of-town. They did not ask for such proof.
RD 12/26, ND 01/09, FP scheduled for 03/06. State-IL. I-485 at VSC.