I recommend giving the diet the whole time suggested. It does take time for things to cycle through your system. Dairy is particularly pernicious--people react up to a month after consuming dairy.
Have you looked into other causes of skin problems (I mean, in addition to DH)? It might be helpful to keep a diary of what you are eating and when you...
Don't forget that oats themselves have a prolamin (avenin) that is similar to the prolamin in wheat (gliadin). Therefore, a lot of people who react to wheat and gluten react to oats, too--oats themselves. If you are eating a diet that includes a lot of oats, that may be your culprit. I react to oats themselves so I have given them up. Hang in there! ...