Very important to practice using a clock before the tournament! It’s not just a battle of wit, it’s also a battle of time management. Running out of time, even in a dominant position, is going to be a loss or, if your opponent lacks sufficient mating material, a draw.
Time management is another dynamic to the game that can give you another path to victory. Or it can be a liability that could cause unnecessary losses. Clocks are not to be feared, so make sure you play some games before the tournament to get used to it!