Once you have your outline, write your essay without stopping for edits. In your outline, you developed a plan of what you want to say in your application prompt, get that plan onto paper. In addition to saving you valuable time as you complete a first draft, there are other good reasons to focus on writing quality only after you have something finished. Many students try too hard to write eloquently and instead lose their own voice in favor of jargon and verbosity. If you are writing quickly, you do not have the opportunity to do this. Once a draft is written, focus on rewriting sentences and detailed edits. For more on this, consider reading Creative Writing Lessons from Daniel Kahneman.