There is nothing to say that a 15 year old is too young to learn to do nails. Provided she can master the skills - and some of these young girls are marvelous -and pass the written assessment to qualify there is nothing to stop her.
The problem may arise when she applies for insurance! Will have to enquire about that one. :?:
Another potential challenge for her is that of credibility with customers. When the majority of clients will be older than this technician, she will really have to perform well and to know her stuff and be very professional in all ways if she is to be the 'authority' on nails - which customers expect. BUT anything is possible. One of our own Ambassadors started in the business when she was of a similar age, and she worked very hard and was like a textbook on nails - she was excellent at her craft and very professional - she has succeeded so it can be done.