When you sit down to write your application essays, there is very little left that you can control. You should have already taken, or retaken, the SAT and ACT, your grades from your first three years of high school are set on your transcript, and your recommenders all have their impressions of you that are unlikely to change before the recommendation deadline. The only thing that left in your control is your writing for the application essay.
As with all things related to your college application, you will need to start drafting your application essay far ahead of the due date. In fact, you should move each school’s deadline up two weeks so that no unexpected events prevent you from completing and submitting your application. The reason that you need so much time to work on your essay is primarily because many schools will ask you to write about similar topics, but to do so in different ways. You will need enough time to draft essays that address each of these questions or prompts for each school to which you are applying. (Citation PWL)