I-90s are taking an abnormally long time of late, due to DACA applications, etc. that are clogging an already severely backlogged application processing system at USCIS. The ones filed by my office all took at least 6 months, but never more than 7. Call the USCIS national toll free number to inquire and also schedule an INFOPASS appointment at your local district office to inquire.
Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
You may also check the average processing times at the following USCIS website which is broken down by application type:
No attorney-client relationship is created or implied by this communication.