I think mine took four to five weeks,
From Wikipedia http://en.wikipedia.org/wiki/FOID_(firearms)
A FOID card legally must be granted within 30 days from the date the application is received, unless the applicant does not qualify. However, by January 2006, the backlog had increased and the State Police were taking as long as 50 days, in violation of the law, to issue or deny the FOID.<SUP id=cite_ref-southern4838_1-1 class=reference>
</SUP> Cards issued on or after June 1, 2008 are valid for ten years; cards issued prior to June 1, 2008 are valid for five years.<SUP id=cite_ref-PublicAct095-0581_2-1 class=reference>
</SUP> The FOID card will be revoked before its expiration if the individual becomes disqualified as described above.