It may depend upon the basis for the petition (in other words, the type of family relationship upon which the petition was based, and whether the petitioner was a citizen or permanent resident).
A case filed in the Immediate Relative Category (a citizen filing for a spouse - husband or wife - child under 18, or adult parent) would likely be filed along with an Adjustment of Status case assuming that the person entered legally, and would in fact be forwarded from the lockbox to the National Benefits Center back to the local office and go through to interview in about six months. I completely agree with the other post here.
If the case was based upon some other classification in the Family 1st through 4th preference classifications (adult children of citizens over 21 - married and unmarried, brothers and sisters of citizens, spouses and minor children of permanent residents, and adult unmarried children or permanent residents though not in that order), then the I-130 would need to be processed alone since the no Adjustment of Status could be filed yet. the case would have been forwarded to the appropriate Service Center for processing, and they process at a much slower and staggered rate depending on the exact type of case.
For Illinois, the case would be processed at the California Services Center if in one of these categories. I attach a link to a page on the USCIS site - from here you can look up processing times at local offices and all Service Centers. Select the California Service Center and hit the button - you will see many entries for "I-130" depending on the type of the case.
I definitely also agree with the previous post that if you haven't even received a Receipt Notice yet, you would definitely want to contact an attorney for guidance and assistance.
Good luck with your case.
Current processing time for I-130 petition takes approximately 6 month. You must have received a receipt from the USCIS acknowledging the submission of your original petition by now. If you have not received any correspondence from the USCIS regarding your case or you believe that your case is outside of the normal processing time you need to contact USCIS immediately to inquire about the status of your petition.
Please contact an experienced immigration attorney to discuss possible issues with your particular case. Immigration law is a federal law and a lawyer licensed in any state can assist you in your case. The responses and information are intended to be general and should not be relied upon for any specific situation. Best of Luck!
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