I'd second what MAppleby has said, given my experience applying to CBS...
I applied to the August 2013 term earlier this year. My interviewer recommended me to CBS, but my application was rejected. My interviewer told me it was the first time in 20 interviews that the school did something contrary to his recommendation. I should note here that my interview report was filed in early March (when many spots had already been taken). I re-applied to CBS for the January 2014 term and was recently accepted, without an interview. Several positive things had happened in the 5 months since my prior application, that made my application stronger - but with all due modesty, I think my first application to CBS would have been accepted if it had been filed earlier.
I think this point is particularly important if you have a common profile (e.g. you're an Indian engineer or white male that works in finance/consulting). That being said, my campus visit significantly increased my opinion of CBS and it provided some useful context when writing my application. Nonetheless, I'd suggest that you apply as early as you reasonably can...