Well, to be fair, the person really wasn't prepared for an Evolution debate, so you had the advantage there. Most don't care to argue the subject, because they don't get trained in the in's and out's of that subject. He was correct in telling you that he is not a Creationist. The Creationists believe that a Creative day was 24 hrs long.
I don't believe in Evolution because I believe that our wonderful planet, and Solar system is so amazing that it couldn't be a matter of chance, it was created by a intelligent designer.
It's not only JW's that believe in Creation that way, but many other intelligent people do as well. If I were there, I think I would have been that sister who stood in the background and didn't participate.