I agree, I also started 2-3 months ahead of time but I am from PCO and this was in concurrence with starting our first rotation so it was a lot of time management and repetition.
I definitely benefited from doing the KMK course-- I feel like they somehow know what questions will be asked.. some were too close to examples stressed to be a coincidence I feel..
That being said, you need to utilize that material and know that you will have to supplement, for example
Contact lenses, Optics, Low vision and to an extent Binocular vision were not covered very well in KMK. I definitely supplemented with our professors' Boards review session ppts for those.
I knew my two weaknesses were Pharmacology and Optics so I spent extra time on those and I ended up getting the highest scores on those two sections on the actual exam.
Recording the KMK lectures and listening to them on commutes, or going back to parts you weren't quite sure about when you jotted down notes during the course helped a lot too.
So again KMK + professor board reviews + repetition. Their flash carts, quizzes, ect. were great resources as well.
Then you'll be more than fine