dpf delete sequence question
 

I looked through the forums but couldnt find the answer to my question. It may sound like a dumb question and i may be over thinking it But I've always had older psd trucks and didnt have to worry about it. I am deleting the dpf on my 08 psd but im having a full exhaust put on it. So when i take it to the shop should i turn the key once its on the lift and set the h&s to dpf off or should i wait until it is done then turn the key and set the tuner? I heard that if you set it to dpf off and run it with it still there it can mess it up. Thanks for the help and sorry if its a dumb question