If you mantain teaching your horse basic manners, get in lots of riding lessons, and take your time - no your not mad.

The more you do with your horse at a young age will be of benefit when he's older. As long as you teach the basics about personal space, no nibbling, no kicking, tying up etc.

Wait until hes at least three years old before you put any weight on his back, or even lungeing - especially if you want a long-term riding pony.

If fact you'll probably find that a sheltand is a lot easier than say a hunter - less worrying as you have less distance to fall off! I'm backing my Dartmoor before my tb, I've backed plenty before - just not my own!