“I’ve never done this before” isn’t an excuse or an apology, it’s an opportunity. There is not historical personal data that you can compare against. You’re setting a new benchmark.
If you’re trying archery for the first time and you miss the target with every arrow you fire, it’s absolutely the worst score you’ve ever received in archery.
It’s also the best score you’ve ever received in archery, because it’s your only archery score!
The first time you try karaoke in public it will simultaneously be both the best and the worst karaoke performance you’ve ever given.
No matter how you do on your first time out you could look at it as your worst attempt, or accept it for what it really is… a personal best.