I did the inquiry for not getting the FP on Jan 24, 2005 (when my I-485 ND just crossed the 30 days timeframe). Today we got for both myself and my spouse's fingerprint request to be scheduled for Mar 1 (mine is with Attorney and my spouse's request is with me).
Last year I inquired for Advance Parole approval and got the approval on the 21st day. So far in my experience of two calls, I got the proper response.