Work Experience

First, those are planning to get an MBA right after college, back out.( Unless you have extra extra extraordinary profile of course ). The schools wont be looking out for you and moreover, you will not gain much out of an MBA without work experience.

Next, the rest of the lot. You would have read about the average work ex in top schools being 5-6 years. Very true. But remember, its the average. That just means there about equal number of students with work ex greater than and less than 5 years.

The work ex is calculated till the time you will be in office before joining school.

Work exp of two years is where you can start thinking about. Three is better. Four even better. the more the experience, the more the schools perceive you to be focused in the career path you have chosen and the more the maturity in your understanding of business.

But here's another view. In case you are planning a shift of career, or deviating for your current job profile in any way, 2 -3 years work exp is a good time to get moving. Once you are completely into your line of work, its difficult getting a change ... say after 6 years. Please note.. its difficult, not impossible.