driege
Just got my interview assignment. I live in Chicago and submitted on 12/14.
I might be alone on this one, but I would recommend that you call first. It seems like Kellogg puts a strong emphasis on interpersonal skills and I think it shows a little bit of confidence to make a 'live' call as the initial contact.
If you get voicemail, leave a message, and say you'll follow up with an email and that they can contact you in whichever way is most convenient for them.