Thanks for your response. You are correct, that is the AAP guidelines. However, the WHO, Canadian Pediatric Society, and many Pediatricians say don't bother at four months for full term healthy BF infants. There seems to be more consensus around six months and utilizing solid foods (incl fortified ones) where possible.
It is also disputed within the AAP as well. Here's a good summary article: <Search for "Experts Challenge AAP Iron Supplement Policy"> and here's the AAP editor letter that originally challenged the guidance: <Search for "Concerns With Early Universal Iron Supplementation of Breastfeeding Infants"> (I would have posted direct links but apparently new members can't do that). There are also some sources online that seem to imply universal supplementation at four months could even be detrimental.
Again you are correct in reciting the AAP guidance, which confusingly our Pediatrician, and a few others we spoke to, suggested we don't adhere by – which is at the root of our concern on this matter for us and other parents given the conflicting advice.