Taking the MCAT in August will put you a little behind at some schools but I personally had no choice last year since I just wasn't ready to take it in April. Like everyone here has been saying, get your AMCAS done ASAP. Then, when you get your secondaries, dont put them off. If you need a composite rec letter from you school, talk to the pre med advisor and see when they could have one ready for you. At my school the pre med committee needed to have an MCAT score before writing a composite rec letter so I had to wait until October when my score came out for my composite letter. If your school has a similar system, speaking to your pre med advisor now may help put you at the front of the line come October when everyone who took the August MCAT needs a letter.
Anyone taking the August MCAT still has a solid shot for acceptance, its just that you have to be a little more diligent about getting the applications done quickly.
Here's what happened to me:
Waitlisted: University of Miami, Mount Sinai
Accepted: NJMS, NYMC, Tufts
Still waiting for a decision from: Albert Einstein
Tufts is particularly good to those who take the August MCAT because they interview groups in the fall, winter, and spring. They space out their spots evenly so that the same number of spots are availible in the fall for fall applicants and in the spring for spring applicants. You have just as much chance of being accepted with a March interview as someone with a November interview, this helps prevent the class from filling up on you before you even had a chance to interview.
Good luck guys, dont lose hope! You'll get through this!