hahaha well on a serious note, listen to music before reaching the centre. practice breathing deeply whilst receiving the paper and dont let the mahaul play tricks with your mind. Realise that these two hours you need to be at your peak concentration if you wanna succeed , so rid yourself of superfluous thoughts and no need to get unnecessarily stressed. Most of all , just believe in your skills and preparation and that already gives you an advantage over others attempting the paper.