While it is too late now to worry about it, this was probably a poor decision on your part. While it is true that the admission process is rolling here at Columbia, the interview process is not. The longer you wait, the lower your chances are that you will be offered an interview. If you do get an interview, when you do it doesn't matter. I don't mean to panic you, you have good stats (lol at the O writing sample btw), so I think you'll still have a good chance of being asked to interview, but you have several thousand applications ahead of you. Columbia is very old school in the admissions process. There is no filtering, so your application is going to be read in the order that it was received.