I would emphasize what the person above said and add that whatever you do, make sure you give yourself enough time to get your mind on a schedule where you can think sharply starting at 8am for test day.
Edit: as someone with a preferred study schedule to you, I started a rigorous routine about 2 weeks before where I would get up, jog for 20 mins to wake up, eat a good breakfast, etc. It helped test day to do the exact same thing and have my brain completely on by 8am.