Y'all, this is so cute. My son started wearing the 0-6 month when he was around 4 months old & it kinda looked silly for awhile. The front area was somewhat poofy and it went up so high on his belly. That size fit him best when he was 6 months old. At 8 months of age & 18.5 lbs, he could still wear them, but the leg openings are a little tight so we have ordered the next size up. Even if it's a little silly at first, your baby will look so cute in these.