Dear Lady Milly & Jack,
Most pediatricians agree that wheat may be introduced around the age of 8 to 9 months old. It's probably best to wait to introduce wheat until you're sure Jack has no reactions to rice, oats or barley.
When Jack turns 8 or 9 months old, start to intoduce wheat products such farina (a mixed grain cereal), wheat toast, and Weetabix moistened with formula or breast milk. PLEASE work with your pediatrician if you are in doubt and unsure about wheat for your baby! This is very important as your infant may have a special situation and the general recommendations may not apply.
Keep in mind that a recommendation to introduce wheat at 8 or 9 months is ONLY based on the fact that a baby has not shown any food sensitivities. It also assumes that neither parent has any wheat allergies/celiac disease or a family history of same. Surely, if either of you have food intolerances, you would work closely with a pediatrician.
And, just to complicate the whole issues, wheat and gluten "allergies" are not the same...
Gluten in wheat is the most the common culprit when people have wheat "allergy" reactions. A gluten intolerance is NOT an allergy nor is it the same as a wheat allergy. Gluten is found in Rye, Oat, and Barley as well as other grains. Since gluten is a component of these grains, this is why you should be okay to introduce wheat to your baby if your infant has not had any reactions to the other gluten grains...clear as mud, right?
Lastly - Celiac Disease or Gluten intolerance, as it is also called, is entirely different from a wheat allergy. If your family has this one, you should definitely take care with the introduction of wheat products.
Hope that helps!