What should I say back? He's getting married?

I'm a runner in college at a d2 university and my head coach is getting married in ten days. He's messaging me right now asking how summer training is going, ect. and I said "it's well, so are you getting excited/nervous about the big day?!" and he replied "only ten days! just anxious :) " What should I say back? I can't just not reply but I have no idea what to say. Congrats seems weird because he's not actually married yet. Good luck seems like I'm cursing him! So what should I say?