Never too young. I have worked with the NY juniors for 40+ years. My daughter showed, her kids, and hopefully my Great Grand kids - but they live in Vermont.
I sponsor a family with 3 kids - the 6th year. I do not believe in getting cattle ready for kids. They work with them as soon as they pick out what they want to show. They do their own halter breaking, walking, stick work, clipping. They are now 18, 16, 13 (were 12, 10 & 7). Now, they help us with anything needed. When we go to a show, they clean all the equipment & pack the trailer - meet us there, unload the trailer, set up display. They are priceless help! They do not live on a farm.