I was so disappointed.  I couldn't even get these on my son's feet.  I absolutely love them though - great colors and really cute, but they were just too tight.  I could get his toes in but not his heel.  I think that it is mostly because he's got super chubby feet, these are just too narrow for him.  I also would advise trying these when your son is in size 4's.  I think my son is a size 4.5-5 right now (since other shoes those sizes fit him) but think perhaps these shoes run small, so if I'd tried them a month or two ago they may have fit him.  He's got a soft-soled pair of pedipeds that are a size 5 and they fit him great.  Perhaps that's because they were handed down and so they were stretched out a bit from the other boy???