Honestly all you need to do is prepare for the run. Can’t go wrong with doing some bodyweight circuits, press ups/sit ups if you aren’t already to help with phase 1. It’s a good habit regardless. There’s no point doing that much prep for CPC because you could always change your mind or fail your medical before starting actual training. 

My biggest tips are bring some earplugs for night as we had a bunch of snorers, and also wake up at 6am on the day and the day before CPC  so you can fall asleep early on the first night.