If your children actually see how you use and how you really make profit on bitcoin and they always heard a lot of times,they will eventually listen and become curious about bitcoin,that will be the right time to discuss them all about bitcoin..
Teenagers nowadays are not so much interested with profits, they want money to spend for whatever they want to enjoy their life but most probably they do not want to spend too much effort to get that, in other words they are just too dependent with there parents.Although there are exemption as some teenager are pretty well train by their parents when they were just a kid but mostly teenager just love to spend but does not love earn.
Some kids nowadays are a bit lazy, I observed that with some kids that I attend to before, they do things that you told them to do, but never finishes it... But if you give them reward, they would do it, which I think is not a good idea to teach a kid... There are also kids who love earning, specially kids that are not rich, they learn things easier too, so probably they are the best one to be told about bitcoin...
