There is no set amount of time at all. If you are eligible to file for citizenship, that is what you should do rather than wait for the 751 decision.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.
You could make an INFOPASS appointment to see if you can find out more information, or if you are working with an attorney see if they can contact your district office to see what's going on with your case.
Ellie Mosko Attorney Ellis Porter, PLC 2701 Troy Center Dr., 410 Troy, MI 48084 Phone: 248-519-9900 Fax: 248-519-9901 Email: firstname.lastname@example.org The information I provide on Avvo is for informational purposes only and does not constitute legal advice or create an attorney client relationship
about 3 to 6 months.
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After waiting another 30-45 days, I think an InfoPass appointment would be your best option. I'm sure the wait is agonizing, checking so soon won't be useful.