Wait until you start buying leathers. Over a 13 month period he had 3 different sets, because of growth.
My youngest son started riding the Strider around the house before he could barely walk. Went from that to a Redline BMX by 4years old, no training wheels ever. Wish I could post a video here 'cause he's FAST!!! When I get home I'll grab the Strider from the garage and post it up for free here