I understand that one can become very excited about the notion of taking on a new endeavor. Yet, there are so many factors that can help determine your experience with a graduate program such as law school that will have a much larger impact on you then what month you can start. Almost everyone would be better served by focusing on the quality of the education, the opportunities to focus on areas of interest, the location/region of the school, the cost of attending, the likeliness of opportunities in your area of interest. Improvements in any of these areas should outweigh the value of a few months of a head start on your next degree.