Janet, she started at 2. She was ready though. It was not expensive at first, just monthly fees, shoes, tights, and leotards, and recital costumes in the spring. When she turned 6 and started competing, then it got expensive, but she offset the cost from ages 11-16 by assisting in classes. She started with just tap, ballet, and gymnastics. She later moved on to other types of dance.
However, despite the cost, it gave her much more than we spent. She has been able to travel, she is not afraid of getting in front of hundreds of people, she learned self-discipline, and it kept her out of a lot of trouble during her early teens.