You really don't need that much time if you have experience writing these kinds of things. I had been thinking about some of the issues I wanted to address since around Feb, thought of an opening sentence over spring break, and then didn't sit down to do it until after finals and when I was back home. Cranked out something 2-3 times too long in two afternoons and then sent it around to everyone I knew. I took a break for a few days and waited for comments. Did a lot of editing over the next few days and got it to the essay I wanted - then it took about another day or two to bring it down to the character limit with some creative editing. I kept playing with it doing some very nit-picky editing with my father (it almost became a sick game with the character count). I submitted it a day or two after the first day AMCAS was open. I was very pleased with it, and was getting great feedback. There is nothing you can do in 6 months that you cannot do in one week - its about yourself, the content is already there. If you are the kind of person who can craft an essay easily, then it shouldn't be a problem to quickly get it done.