Most girls who do ballet, dream of the day they can get their first pair of pointe shoes. However, it is not as simple as age or years of ballet that determine when to start pointe.
Dancing en pointe changes the direction of forces through the foot and does not allow the foot to use many of its shock absorbing mechanisms; in fact, when en pointe, the force transmitted through the foot increases by 12 times the body weight. Additionally, when most girls start pointe, they are still growing, which means there are still the soft parts of the bones known as growth plates present. As you can imagine, if your feet are not strong enough when you start pointe, you are at risk of injury and damaging these growth plates.
In addition to needing strong feet, the flexibility of 
your foot is very important. If you have stiff feet, it
can make it difficult to rise right up onto the box of
the pointe shoe without bending your knee.
Sometimes, girls get pain at the back of the foot from trying to rise up and may develop posterior ankle impingement, which may require rest and/or boot immobilisation. Gentle stretching of the foot can help to improve the flexibility, however it should never be painful or forced.
It is not only your feet which need to be considered to know if you’re ready for pointe. The ability to maintain good turn out from the hip is necessary as there is no way to cheat your turn out en pointe, and may put you at risk of knee or ankle injuries. Also, good core strength is needed to help maintain a neutral spine and pelvic stability. Finally, balance and proprioception play a vital role, as when en pointe, the base of support is very small, making it much more difficult to balance.
What to expect in a pre-pointe assessment:
1. A thorough review of your dance history, any history of injury or illness, as well as general background information.
2. Assessment of foot and ankle flexibility as well as range of motion of hips.
3. Assessment of foot and ankle strength, deep turn out muscle strength and core muscle activation and strength, including the use of Real Time Ultrasound.
4. Assessment of balance and other functional assessments.
Following the assessment, specific exercises may be prescribed in order to correct any insufficiencies prior to beginning pointe. It may take a few assessments before you meet the criteria to begin pointe work safely, but if you complete your exercises as prescribed you can progress quite quickly.