We bought the 6 month size, our son is 7 months but on the smaller side. The onesie fit, but it probably won't get too many more wears. We paired it with black pants and a little hat - it was really cute. The only reason it doesn't get 5 stars is because the bow ties that come with it is not a very nice material or colour. We actually order a matching Dad and son Tie/Bow-tie and had a local alterations place but a button on the bow-tie so we could use it on the onesie. That worked out great!
Absolutely love it!