When Is the Right Time to Bring This to My Child?

When is the right time to bring this up with a child? I've heard as young as six. It's almost like you're trying to, you're not redefining sex, but because sex has been so distorted, you have to redefine it from God's perspective. And they have to see it as a beautiful, good God given gift,. Not as this shameful, horrible thing that needs to be done in secret.