New job anxiety

I had a bad experience at my last job being put on a shift as a trainee on the busiest day of the year and left on my own. I’ve recently started a new job and I have my second shift this weekend for 6 hours. Saturday’s are the busiest and I’m so stressed because I don’t want to mess up and get in trouble or embarrass myself. I get myself so worked up over this and it stresses me out to the max. I get very overwhelmed and anxious when it’s busy. What Can I do to focus on the positives of it being busy and what Can I do to cope and handle it?