Sounds like you have a lot of bases covered - would suggest that you now get him used to everything - condition him to trust you and not to worrry about flags, people, dog barking ... (things that may happen at a show and more) - make sure that you are in situations that you can win because the worst thing is to have a bad experience (for you and the colt). One of the best colt trainers I have ever seen is Larry Patterson of VanBert Farms. If you go to their site (vanbertfarms.com), you should be able to find a video of Larry training a colt. Larry wins at halter classes because he has colts with good conformation for halter classes but, most importantly, because he has worked with his colts in every situation so that they stand naturally. Best of luck.