Make sure you have a breakfast containing of course Low GI carbohydrates and ensure that you are adequately hydrated for this endurance event (3hrs).
Your hand is going to have to sustain constant isometric contractions that at times will feel fatigue like symptoms relating to an accumulation of metabolic by-products like lactic acid, and in particular an accumulation of hydrogen ions. Hopefully your year of training has increased your Local Muscular Endurance.
The Legal ergogenic aid "caffeine" will not benefit you in the slightest tomorrow and i suggest avoiding it.
Your arousal levels could at times slip to low levels so you may have to perform arousal promotion techniques like positive selftalk and breathing techniques to fire yourself up.
What up pe.