Its the getting it right time that I worry about. Most kids don't have the luxury of being perfect before thrown into the fire.
If I only have a short window of time to work with a kid, I'll focus on stance and protecting the throwing hand. Part of protecting the throwing hand is catching one-handed, which goes against what every kid is taught when they first start playing catch. I will get into a NR stance and simulate catching the ball with my hand flying up next to the glove, and freeze at this point. I ask them what THEY think will happen if there is a foul tip (busted fingers!). This has never failed to get them to understand - clearly - the importance of protecting the throwing hand. WAY more often than not, their old habits disappear quickly.