I think the "correct" order is whatever way works best for you. You should try it both ways and compare results.
Personally, I always do mine as a pre-shampoo treatment. Results are best for me this way.
It's a great question because I think a lot of people are wondering with the newer "Hair Masques (Masks)". Some say to use as pre-shampoo treatment and other say to use after you have washed much like a deep conditioner.
I was reading an issue of Allure magazine lately and found it curious that they suggested doing a deep conditioner after washing, and THEN re-condition with your regular conditioner. I have never done that.
Cheers,
Jade