I haven't heard of any exact time period it takes to get your name check after the interview. If nothing happened after 90 days, you probably want to set up an infopass appointment and try to find out what is going on. Sometimes, this may get things moving. If not, you may have to start getting in touch with your Senator, Congress people etc. Hopefully, you will hear from USCIS soon. I have been waiting over a month too though I was verbally approved at the interview and didn't have any name check issues. Oh well!