If your home takes 90-120 days to sell (sorry for that grim advanced news) and July is the peak selling month in Lincoln Park (which it is), then March 1 or sooner....ASAP. If you've signed with someone make sure they tell you what the absorption rate is for your specific home.
If they ask what an absorption rate is fire them and give me a call. Good Luck!
Chicago offers an extremely busy January market - so I unabashedly advise you to get your place on the market as soon as possible. In the past eight years January has typically been my busiest business month. So far this year I have witnessed a significant increase in calls for my listings and my clients and I have sold one Andersonville townhome while we expect to finalize another contract on a new construction home in Bucktown sometime tomorrow. Good luck with preparing to list and aggressively marketing your home. Feel free to email me with any additional questions at firstname.lastname@example.org or call me at 773.848.9241.
All the best!