I took my MCAT in early June 2016 and submitted my primary a few days after the application opened (June 6 or 7?). However, I didn't have my score at that time. By the time I got my score in July 2016, and the score was not so pretty, my primary application was already certified by the AAMC. At that point, I just decided to go for it and complete my secondaries. A year went by, and I did not get 1 interview. All denies.
Now, depending on your score, you may or may not submit. If you have a score over 510 with a solid GPA, experience, volunteering, etc. then you could submit. I think medical schools initially filter people based on GPA and MCAT score, so if you already have a fairly strong range for both, then you could submit.
I'm retaking my MCAT on 6/16 and will not get the scores until 7/18. I'm not submitting anything until I get the score. I don't want another situation like last year.
I think having your primary application certified by August, is still not considered late. It's not early, but you would be with the other batch of students.
Where do you currently stand with your MCAT score? Does it look good/bad/meh? Why are you retaking?