Keep your cool and concentrate on your own work, not what others are doing.
Make sure your model has great hands and nails.
I think (not positive, you would have to check) that you can do a lot of your prep before the competition so that you can spend longer on the actual acrylic.
Make sure you have all your kit prepared and double up on everything just in case you have a problem on the day.
Enjoy it!
You'll do great. Good luck x