1. Teach them what 'money' is as soon as they understand the concept.
2. Teach them how 'money' is 'created' as soon as they understand the concept. At this point they should then be ready to move on to..
3. Why there has to be an alternative.
But at what age is that? The true concept of money is hard to understand for kids. Heck, most adults dont even understand it.
I bought my niece a silver coin for her 5th b'day. My sis thought I was nuts lol. I guess no age is too young to start.