It’s time to stop thinking. Turn it off and allow yourself to absorb the entire experience like a sponge. Don’t second guess anything you have done to get there. Don’t second guess anything you didn’t do.
You have done what’s right.
Trust in yourself and all of the hard work that you put in. Don’t question whether or not you belong in the company of those athletes you are staring at in the village or those squeezing in their last training session.
You do. You probably belong there more than many of them do.
The work is done. Now you have earned the right to dance and party your way through 140.6 miles of life changing bliss and “discomfort”. Your entire day will be cyclical. Up one minute and a little down in the blink of an eye. Just understand that the rebound isn’t far behind the fall. And you WILL cross that finish line. And you WILL be an ironman.
Be proud but stay humble or so help me God I will personally hunt you down! 
Be safe, have fun, and THANK THE VOLUNTEERS.