I kept wondering when he was going to fit in it (it looked huge), until I looked up Gymboree's sizing chart and realized the 3 meant 3 years old. In hopes of not making that mistake again, or the chance of missing and adorable outfit I looked up the sizing chart for the most common baby clothes.
Here's a more practical guide (not so cutesy).
Does anyone else have a hard time moving their babies up to the next size clothing? I do! It is just so hard to admit he's growing up that fast! Baby Boy has high water pants and stretched bodysuits before I finally switch him over. It is fun to see him in new outfits though!