Up to the interview, you are fine, but after the interview, it is up to the district court.
My case was delayed at the court a bit, and the court holds oath ceremony once a month in my case.
So, after all, my case was delayed about 2 months compared to others who had the same day oath.
Regardless the delay, a good thing is that (if you plan to change your name anyway) you save money and headaches afterward.
* N-400
08/08/2007 : GC Rcv'd
05/07/2012 : N-400 mailed
05/14/2012 : PD
05/18/2012 : NOA Rcv'd
05/29/2012 : FP notice not Rcv'd
06/27/2012 : Infopass for FP
07/05/2012 : FP done (walk-in)
07/10/2012 : In line for interview
08/20/2012 : IL mailed
09/25/2012 : Interview done; Name Change Requested
11/19/2012 : Oath Done with New Name
*N-600 for My Children
11/23/2012 : N-600 mailed