Finance I believe as far as what money is, and how to take care of it...say about 5 yrs old is a good age.
It needs to be done very simple, because that is how most people learn.
Law about the same age.
It too is a vital part of being a responsible part of the community, and a healthy respect for the law.More so for boys, than girls.
So like with people like myself, having had 3 sons....it was taught very early to them.
Boys get up to more mischief in the main, but it must be part of any Girls life also.
We may not like some parts of the law, but we all have a common ground, that we must follow it.
On saying that....it should be done in a good way, and not drive home a total fear of ....To the point that it could cause rebellion later, in teenage years.