As a mother who put her son on ponies from the age of 2 onwards I am in agreement with LHP. Son went off lead rein at 4 on a pony like that palomino. A seen-that, done-that, bomb-proof, fox-hunting proof, puddle-proof, helicopter-proof, gymkhana trained, jump-trained 16 year old pony. THAT's the sort that gives a child confidence.
You son wants to hear you say "just kick on, he'll be fine", he doesn't want to hear "be careful when you do that" or "hold on, I'm coming" or "I THINK he'll do it, let's try"
Get up, get going, seize the day. Enjoy the sunshine, the rain, cloudy days, snowstorms, and thunder. Getting on your horse is always worth the effort.