What a great idea.
Here's another thought, you may want to think about charging a set fee for the class as a whole. That way you would have the $$ up front and they would be more inclined to continue the class until their piece is done. When making your sample, you might want to consider keeping track of your time to see how long it takes from start to finish and guage your fee and class times by that. Even though it's for family, friends, etc. I'd be cautious about them taking advantage of your time and talent because of that fact but you can still be as flexible as you want to be.
I think the relaxed environment of your home is a great idea for you, your girls, and the students. I know I would like that type of environment myself if it were me taking the class.
You have a great idea, have fun with it, you never know where it might lead you.
Now, when does your first class start.....can I be your 1st student? lol
Deb