George Balanchine was a master of choreography on pointe and was the one who created the "baby ballerina." He is reported to have said “that there was no reason to get a young dancer up on full pointe if she could not do anything when she got up there!
It is VERY important that you are at least 12 years or older. Why?
Children's bones are extremely immature and soft. While we grow and develop, our bones go through the same process. If you were able to look at a young persons bones, you would see that there is cartilage and not bone at each of the ends, these are called the growth plates. These growth plates will not finish growing until much later in your life, usually around 21 years old.
As you reach 12-13 years, the foot growth will start to slow down, and the hardening process will begin. This normally coincides with the onset of menstruation or your second growth spurt. When periods begin the hormone oestrogen is secreted by your body, it is this hormone that will keep your bones healthy, strong and solid.
Waiting to go on Pointe can be frustrating, but be patient it will be worth it in the end.