Choosing a title is personal. It is what communicates the heart of the matter in your essay. The title should reflect your style and your substance. When to create a title is a matter of preference.
Some people like to write it first, using it as a banner to guide the rest of their work.
Others prefer to write it last, after they have experienced the full development of their work. Either way, when you decide to create your title, brainstorm as much as possible before choosing. You might want to think of your title as art with words. Play with words. Create a pun.