The next day I glued the mirror on with the Loctite PL520 Mirror adhesive. It is very important to use the right kind of adhesive with mirrors or else it can pull up the silvering on the back. I let that sit overnight with some weigh on it to.
Since it weighed a ton, I used a french cleat on the back of mine. All you have to do is attach it to the mirror and attach the other side to the wall and it locks in place.