Profile Evaluation, please

Hope to matriculate Fall '13 but may wait until Fall'14. I will be either 26.5 with 4yrs FT or 27.5 with 5yrs FT work experience. Is there an advantage to waiting? GMAT - taken twice thus far. Currently sitting at 620 with a 41V/34Q. Education - 3.1 GPA in Political Science/minor econ from top 20 US...