I like to do as much of the cutting and welding mounted on the frame before the body is blasted.The way you should be doing the body work now you could have it blasted first and then selfetch primer it.All your bodyfiller should be put on over the etch primer NOT to the bare metal as was thought years ago.So.....its up to you if you get it blasted it must be primed pronto(like the day its blasted).