You will probably be advised to start with a single grain cereal such as rice, oatmeal or barley. (organic-baby-resource.com)
When choosing a high fiber cereal, look for whole grain cereals as they supply the most bran (a mere 1 / 3rd cup of bran contains about 14 grams of fiber). (whfoods.org)
Start with a small amount of iron - fortified single - grain cereal mixed with breast milk or formula. (kidshealth.org)