I started using MCN when DD was 3 months old. I bought Itti Bitti D'Lish snaps in medium and she was out of them by 9 months old, but I loved them so much that I bought a set of large and she is still in them now (17 months old). It looks like she'll continue to fit these for ages. At the same time I got some green kids pockets, however, I thought they were too bulky until she was about 10 months old. They are are perfect now but she loves to undo the velco