When it comes to personal finance, it is never too early to teach your children the value of money. The younger they learn of its importance and effect, the more capable they are of making sound decisions.
Children should know that money is not something to ask from parents or relatives. They have to know that they should earn it by working, doing errands. You can also give bonus for doing good deeds like doing well in school, helping the neighbor or a good deed.
They should also know that they should allot money for the rainy days and they must understand that you would not give them money all the time. It might be too early to explain tax, but you can explain how to allot money into different categories like spending, savings, charity, or emergency fund.
Although your children should sound excited about these money information, you should also imply to them how important it is to donate to charities and give back. That way they do not revolve their world around money all the time.
If you can make your children understand the importance of being smart about their money, then that would make a big deal when they are growing up and they have to make all these choices for themselves. They may not save up as much but it would keep them from overspending.