Gap in employment after univ degree

I had a similar situation - graduated in May, started work October 1. My approach varied by application. Some specifically said to explain gaps and so I added a brief explanation (e.g. "the job offer I accepted during college specified a start date of Oct 1, during the gap I studied for the CPA exam which I passed on my first attempt in Nov."). For the applications that didn't get so specific about work history I didn't include an explanation and just started my work history on Oct. 1. I think schools understand that many people don't start work the day after graduation, so they shouldn't hold it against you. Neither my Kellogg nor my Duke applications had an explanation for the gap, and I was admitted by both.