As soon as you feel well on an elimination regime, you can begin testing, although you must not do so before the four day unmasking period has elapsed. Allow longer if you have been constipated.
Of course, you may never improve on an elimination diet. The problem may be something else, not a food. In that case, when three weeks (maximum) have elapsed on the simple elimination diet, two weeks on the Eight Foods Diet, or seven days on a fast, then you must begin re-introducing foods. This is vital. It is not enough to feel well on a very restricted diet; we want to know why? What are the culprits? These are the foods you must avoid long-term, not all those which are banned at the beginning.
Even if you don’t feel well, as already pointed out, this does not prove you have no allergies amongst the foods you gave up. Test the foods as you re-introduce them, anyway – you may be in for a surprise
My recommended procedure is as follows, except for those coming off a fast:
Eat a substantial helping of the food, preferably on its own for the first exposure. Lunch is the ideal meal for this.
Choose only whole, single foods, not mixtures and recipes. Try to get supplies that have not been chemically treated in any way.
Wait several hours to see if there is an immediate reaction, and if not, eat some more of the along with a typical ordinary evening meal.
You may eat a third, or fourth, portion if you want, to be sure.
Take your resting pulse (sit still for two minutes) before, and several times during the first 90 minutes alter the first exposure to the food. A rise of ten or more beats in the RESTING pulse is a fairly reliable sign of an allergy. However no change in the pulse it does not mean the food is safe, unless symptoms are absent also.