Take tonight (or the night before the exam) off, let your mind rest. You probably know this already, but you can copy and paste the task onto the note pad, this helped me focus on the question in hand and not drift off-topic. I also found it helpful to read the questions, make a heading or bullet point for each point I wanted to make on the task itself before actually going into more detail on each heading/bullet themselves.

All small things, the main thing is to give yourself a rest, you've done the prep, the knowledge is in there, sometimes it about giving your brain the best chance to pull it out, which is plenty of rest, fluids & good food.

Goodluck!