From biometrics to interview date it took five and a half months but I think our particular service center is really backlogged. It took four and a half months from biometrics to get our interview notice. From notice to interview my husband had 5 weeks. Perfect amount of time to study. :-)
Here is the link to the offices and processing time. https://egov.uscis.gov/cris/processTimesDisplayInit.do I wouldn't put much weight into the processing times but you would be able to find the field office that is closest to you. That is where they do the N-400 interviews, etc. Good luck!