I don't think trading will make them financially independent, that's what investing will do and I'll make them pick interest in investing from a very young age, I won't force then though. I'll employ an approach that'll involving them saving some fractions on their allowance and I'll invest it for them at first. When they see the return of their investment on their initial capital and this trend continues, with time I'm pretty sure they'll pick interest in it and start doing the investing themselves.

Investing isn't common in my family and I'll have to end that traits because it isn't a good one. Trading on the other hands, if they are to pick interest in it I'll make them understand it shouldn't be a career path but can just be a hobby because I can't imagine my children steering at the screen all day, that'll result to some deadly health issues especially those relating to the eyes.

For the age, the earlier the better, 10 should be appropriate but if I noticed they have begun developing interest before 10 I won't stop them.