I am Legal Permanent Resident of US and I have filed I-130 petition for my wife on February 2012 and case is currently Pending at California Service Center. Coming week, I am becoming Naturalized US Citizen and I understand that after I become naturalized US citizen I have to request USCIS to upgrade my wife's I-130 petition to Spouse of US Citizen. As per my knowledge,currently, I-130 petition of US Citizen's Spouse is processed only at local USCIS field offices not at USCIS Service Centers.
So what happens when I inform USCIS to upgrade my wife's I-130 Petition? How it will be processed? How long USCIS will take to process our I-130 petition? Will California Service center process our I-130 petition or it will be sent to local field office?Currently my wife is living abroad and she have never come to US.