Generally what I would do is start the colts on their very first ride just a couple of circles being ponied by another horse. The halter is on underneath being held by the rider on the horse, the rider has the reins but doesn't pull on them. Then on their first solo ride I go in a snaffle. I just notice a lot of people riding their colts first in halters so I was wondering. I don't see anything wrong with either, so long as you aren't yanking that snaffle through the colts mouth.