You can travel up to three days prior and three days after the beginning and end of your scheduled trip (doesn't even have to be a deadhead). Not 72 hours (as explained to me), but 3 days, so that can actually be a little more advantageous to you.
Should be very simple if you are just showing up to your destination a few days early, or leaving a few days later. A little more complicated if you are going elsewhere, then to start your scheduled deadhead. And yes, it's a deviation ticket.
Love that cowbell, one of my favorite SNL skits ever!