Shooting out off the starting line from adrenaline is always a mistake. You chose wisely! Most folks shoot out like a bullet and run their fastest mile, then they have a difficult second mile and do the "dying man's shuffle" in the final mile. BAD.
Smart racers negative split races. That means you start out at an easy comfortable pace and each mile you pick up your pace. On the final mile, you are warmed up, in your groove and running your fastest mile. You pass all the people doing the dying mans shuffle and it boosts your spirit and energy even more. This is the best way to use your energy for racing and maximises performance. It also feels awesome. I try and negative split every run other than my really long ones. On those I'm just trying to maintian my pace and finish the distance. Once I lock that distance in I can focus on speeding up.