First off, I'd like to say I'm not one to show before my horses are 2 years old. I believe they shouldn't be pushed too much souring their first year; they need to understand people are good, and "fun". At about 1 year and a bit I start to have expectations, then by two years I'll show. I have as much time as I need to show a horse, so rushing into the first year is not my thing. I also think mentally they have a hard time with showing, because their attention span isn't great yet. But, thats just my personal opinion! I know many people will disagree.
I would make sure that the colt is used to people touching him. For example; His feet will need to be picked, you will have to get him used to the clippers, he needs to let you touch him everywhere.
He should stand tied so much it just becomes an expected part of life.
Have you trailered him much?
Has he been in big groups of horses and people?
Besides everything I already mentioned you have to do all of the halter/showmanship training.
The more the better, but for minutes at a time. If it only takes 30 seconds...Great! Then play with him for 10 minutes... Then train again.
Please, please, please be careful not to push too much. This little guy needs to be mentally ready or else you'll sour him.
After re-reading the question I'm not sure you said his exact age, so if he's not under one then my first paragraph isn't exactly what I'd do:)
"On the 6th day God created horses; and on the 7th day He painted the good ones"