Seeding now in Chicago is generally a waste. What makes you think the
seed is going to wait till next spring to germinate? What will happen
is it will germinate now, but most likely not have enough time to get
established before winter, which will kill most of it. The time to
have done this was a month ago. The only case where I would seed in
your area now would be if I had bare ground. In that case, I'd likely
use an annual rye for some quick cover for the winter.

In your case, I'd wait till spring to seed.