After the COPY of the notice of petition and petition has been served, the person who served it shall fill out an Affidavit of Service. Step 1: Give your tenant a Notice and wait the amount of time stated in the Notice.Illinois law requires the Cook County Sheriff to enforce evictions in Cook County. The only entity that may evict a tenant is the Cook County Sheriff. After the tenant is served, you must fill out the Proof of Service and sign it. From the date we submit the fiveday notice to them, it takes them 710 days to successfully serve the tenant. Try 4-5 times and then post the notice on the door. After the tenant is served, you must fill out the Proof of Service and sign it. Try 4-5 times and then post the notice on the door. If you serve the tenant an incorrect format of the fiveday notice, weeks down the road a judge can throw the case out.