Big Shoulders Question

I plan on doing the Big Shoulders Swim in Chicago next month for the first time. Will drive up from Cincinnati on the day before. If I go to the Ohio St. Beach the afternoon/evening before, is it likely that I will get in a warm-up swim? If not, is there another place on the lake that would be good to get used to the lake? I have a reciprocating Y membership that will get me into the Lakewood Y, but I'd rather swim in the lake instead of a 20y pool. Thanks for the help, and to all of you who have said that this OWS is addictive, you can say that again.