What should a 6 month old colt be learning?

We are getting a new baby next week! Well, he is a mini (lol), but pretend he is a pony, haha. I want to teach him to ride (please don't inform me of the risks, I know. I am training him for little ones to ride, would you rather I stick a 2 year old on him for the first time? I won't be riding him regularly, and I won't even get on him until he is 2-3 years old) and drive. What should I be teaching him (besides obvious leading, picking up feet, you know, handling/barn stuff)? WHEN and HOW do I introduce him to the bridle, bit, harness, cart, saddle, girth, etc.? Thanks!