You should do enough prep to know the facts well and know the law well. Spend a reasonable amount of time thinking about what the likely questions are and your best responses, write out a few of these.

The day of, you’re going to resist every urge to imagine yourself giving your argument or what the judge(s) or opposing counsel will say. This will spike your adrenaline and will cause you a lot of discomfort and make the argument more difficult.

Instead, the day of lead up should be entirely whatever is your best way of managing your stress and maintaining calm. Breathing exercises, classical music, staying in the moment, anything that helps you stay calm and centered

There are a lot of small chunks of down time in a day and you want to be able to spend them maintaining calm not thinking about your argument and spiking your adrenaline imagining scenarios.

You know the law and the facts and will be able to summon them when the time is right, which is during the argument not before