USC or UCLA Part Time MBA? Please advise

I have a quick question. I graduated UCI in 2009 with a BS in Biomedical Engineering and a GPA of a 3.27. I worked for a very large biotech firm for a year and then went to work as a business development consultant for a local company. Last year, I started my own business and its been more than successful. I took the GMAT over the Summer and got a 620. I was planning on retaking it, but my business has been doing so well, I didn't want to put the time and energy necessary to really increase my score. I was looking at the USC program the other day and their night program matches VERY well with most of my scores. The one huge setback is I have 2 years work experience (minimum) and I'm only 23 (minimum). I have 2 amazing letters of rec (1 from my old boss at the big biotech company and the other from one of the vendors I work with in my business) and have pretty good essays. What are my chances? What can I do to improve my chances?