In terms of infant formula vs. follow on formula, I used Nanha. When my son turned 6 months, I was actually still breasfeeding mostly and only gave him a top up bottle of formula at night after the last BF. But I asked my pediatrician about Nanha1 vs. 2 (Nanha 2 is the follow on formula for the Nanha brand) and she told me that since I was only giving formula once a day, I could switch to Nanha2. I think that if I had been giving only formula and no BF, she would have told me to stick with Nanha 1 for awhile longer. She mentioned that the reason is that follow on formula has more protein in it and maybe at 6 months, if you give only follow on formula, that is too much protein for the baby's digestive system at that time. I don't know if what she talked about only applies to Nanha or to other formula brands as well, but that is what she told me. Not sure if you use a pediatrician or not, but if you do, why don't you just ask him/her? I find my pediatrician a great source of information and I can always call and ask her stuff.