Two things-
1)
Accept you're nervous- this is a big day, it's absolutely understandable to be nervous. It only adds more pressure on you if you keep trying to kill the nerves- they're there because you care about this and that's not necessarily a bad thing (in healthy amounts).
2)
Do something fun- dance, watch a movie, eat something you love, engage in an activity you enjoy. Anything that lets you enjoy this massive achievement. This will also help turn nervousness into excitement and enthusiasm.
You've got this- I'm rooting for you!!!