T.F.
Sounds to me like your children want to do this ONE activity but you "drag your feet" because you don't want to take them and follow through.
Don't make excuses with the homework, etc... Family schedules can be worked out for children to have a life outside of school. It takes a bit more effort on EVERYONE's part.
It's not like they want to do 3-5 different activities. Yes, the younger you start in something the better off you are, especially if you are good at it and it helps you later in your school career as well.
Dancing to your children = fun. In reality it is also excercise, socialization and something the helps them build character.
I say go for it. Take a good book to read or magazines to catch up on while you wait. You might make some friends too!!