We always have our kids feet measured at Nordstroms. They are awesome and won't sell you anything unless your son really needs them! We recently brought our kids in, they remeasured their feet and said that they both have a few good months to go before needing any new shoes! Wow! What amazing service!!
They also make a big deal out of the kid's first walkers! Balloon and picture! They spend a lot of time making sure that the shoes fit and they have growing room, but not too much! And the best part is the shoes tend to last a lot longer then shoes we've gotten elsewhere - great if you're looking to pass them down!