I teach many kids in many formats. They always use fingers first to learn the mechanics. I hope, before you bought the bow you checked his eye dominance.,
Obviously the draw length needs to be perfect to anchor properly, hand position correct to avoid torquing later on and string slapping the sensitive skin on his forearm.
Many things such as release, follow through, etc can be done indoors on say a rainy day shooting a string bow.
I know I'm giving more of an answer than you asked for but I'm only trying to help.