Enjoy yourselves, dears. Once the ceremony begins, there is nothing more you can do. Just let it go and have fun, and forget about stupid details. Everyone is there to celebrate your love and the beginning of your married life. Remember that.
(Also, it's a good idea to put someone in charge of everything - other than the two of you. Make sure you have someone who will intercept the "problems" so they don't reach you, otherwise you won't enjoy a minute of your day, and let me tell you it already flies by as it is. The kitchen wants an info? X will answer. The DJ has a problem? Y will deal with it. And so on and so forth.)