To me this shouldnt be done. Ever been smoking with a friend and then they get the smart idea to get a handfull of cheetos or doritos then decide its time to take a hit after and they get food all over the pipe or bong? yea. Not fun.
I say smoking after is the way to go. Just my opinion though.
eating doesn't kill my high too much, and i'm usually high again before i'm sober. though to stay healthy i sometimes prepare a healthy meal before i get high so i'm not as hungry when stoned.