Commenting because you asked.

Never deviate from your normal routine during important events. Your normal routine should be enough to get you through whatever your are doing: competitions, exams, etc. if it isn’t enough, change it, but don’t change things the day of. Doing so runs the risk of introducing change that can negatively affect you. Even things like eating breakfast before your exams (when you don’t normally do so) could give you IBS or taking medication that you don’t normally use can harm your ability to focus or forget things.