But first, you should list what you need to do: research, write the draft and finalise. Then, plot these on your calendar planner. Schedule finalising your draft a couple of days before the deadline so that you will have cushion time for unforeseen oversights. Make the first day of your research now or, if there is not enough time and energy left for today, the first thing tomorrow. In other words, do not waste time and start the actual work promptly.
As mentioned, you need to carry out your plan as soon as possible. After making your plan, you have to carry it out. Do this right away. See to it that you follow your schedule. Writing your essay is about what you need to write and knowing what you need to write means that you should actually do research work. In other words, the problem of essay writing worrying what to write and worrying is about not doing anything. When you carry out your plan, you are actually doing something and when you do so, you stop worrying. The two are opposites and do not come together. When you start working, you stop worrying. When you worry, you are not doing work.
The task of writing your essay is an overwhelming task. But you are overwhelmed only because you are not doing anything through worrying. To be able to do your essay, you have to take action promptly. Start by planning right away and making this first step a short one so that you can proceed with the actual work immediately.