They process based on the Notice Date of your I-485 receipt, and currently the processing time is 10-15 months. So if your case is about 1year old, you should get an interview notice in about 3 weeks. And the interview should adout 2-3 weeks after the interview notice. And the fingerprint expires after 12 months.
For my case, it tool a week to transfer. You can go to Denver INS to query. Be sure to ask them to give a fingerprint notice if your fingerprint is more than one year old. This just save your time so you may have your stamp the same day as the interview.