After you have prepared your ideas and written a plan/outline, you are ready to start writing your first draft. Note the word "first". A mistake we often make is thinking that once we have written a draft, the essay is done. Not so; the first draft is only one part of the whole writing process that leads to a finished, presentable, and hopefully excellent essay. The idea of the first draft is to get the ideas out, to flesh out your answer, and to give you some content to shape and change into a finished essay. You may need to write a number of drafts in order to get to that final essay. Or, possibly, if you have really thought through your ideas and planned well, you may only need to write one draft that you then edit. It depends on what happens in the first draft - and it is best not to expect too much or too little from it.