I took it in August '01 and if I had it to do over again I would have taken it in April. I did better than I would have done in April but I feel that your best chances are going to come from schools that have your applications early, and not be waiting on your MCAT scores to come in. The best route is the one that oldman mentioned, because I'm sure if I reapplied with my August scores for next year's entering class then I would fare much better.
The bottom line: if you can take it in April, then do so and then get all your stuff in early, if not then take it in August and if you can, then wait a year to apply. Just my two-cents. Good luck to you! Ciao.