I too took the MCAT August after my sophomore year. I took a prep class over the summer, but before that I had AP credit for all English classes, Intro bio 1 and 2 with lab, Intro and organic chem, (both one and two) with lab, a molecular and cell bio class (the BEST bio prep by far, covered SO much of the bio section), and one semester of human anatomy&phys with lab.
I had no physics, which isn't what I would recommend, but I absolutely am SO glad I took the MCAT when I did. It gave me time to retake and not be late at all if I needed to, also, when all of my other friends were stressing about the biochem test the day before the MCAT, I was fine. It totally eliminated all outside stressors because I dedicated the whole summer to the MCAT. If you can swing it, do it. 🙂