a 29 is not a bad score by any means. MCAT scores of accepted applicants generally average around 10 for most schools, although a 29 is less competitive at the very best schools. but remember that your MCAT score is only one part of your application and that the MCAT isn't going to be what gets you into or gets you rejected from med school.
in regards to your question, you actually have to indicate on the AMCAS app that you plan on taking the august MCAT. this means that if you indicate that you plan on taking the august exam your file won't be reviewed until your august scores arrive sometime in october. this can be good or bad. if you don't have decent grades to back up your current MCAT scores or you're only shooting for top schools, then assuming your scores improve, waiting on your file may be beneficial. BUT, many people do the same or worse on MCAT retakes--plus, your file is just going to sit in every single admissions office you apply to until october while everyone else who is NOT taking the august MCAT is being offered interviews, etc, etc. so you need to weigh the pros against the cons here. realistically your score isn't going to hurt you unless your grades aren't very good.
