...Just remember if you are promoting yourself as a wedding singer you are going to have to preform regardless of how you feel on that particular day!
How true that statement is... I have thought to myself many times "Man, if I had to sing tonight, I'd be hooped." because my voice was screwed up due to a cold or whatever... With weddings, most of the time where you're set-up is not conducive to singing. At least not to me...