You may want to talk to your demo and see what ways she will support your business. She will benefit from supporting your business if she does share craft fairs and customers.
I sent out a letter to all of the customers that my first downline and I both knew and let them know that we both felt comfortable with whomever they chose to do business with. You and your upline should not be competing, you all should be a team and support each other!
If you think that is not going to be the case then I would definately make sure you have a few friends who can help you meet your goals. But I also strongly agree that it is worth a shot at starting your own business, if it is not going to be a financial hardship on your family.
You also may want to look at what type of services your demo provides. Does she have a lot of workshops and classes? You may find some customers for yourself, doing something she doesn't provide.
I find that I have a lot of customers that are beginners and then slowly learn techniques as I have different classes and look for the best bargains (like me!
). My downline has more customers who like to pay for convienence items, like premade packets, and more advanced techniques.
If you have a love of SU products and have fun using them you can be successful! I wish you lots of luck!