Only a few children are ready to start learning piano before the age of 4 years. I do teach a few very young children but we do general music (movement/dance/singing/beat-and-rhythm/story/make-believe), introducing piano very slowly.
4-6 years: Early beginners. At this age it is essential to have a supportive parent who can make music fun in home follow-up. Time is split between piano work using a simple method e.g. Piano Safari or Dogs and Birds, and mat time.
7-8 years: Mid-age beginners. This is a good age to start if you want your child is be a little bit more independent and pick things up a little quicker. There will still be mat games to follow up on music essentials, but more time is spent at the piano. Please note you will still need to support and help at home at least some of the time.
9-10 years: Late-age beginners. At this age children are able to work more on their own but you should still be very supportive and help where you can. It is important that children starting at this age work on their new skills every day. Stagnation can easily happen if the fundamentals are not grasped quickly.
Mature-age beginners: It is never too late to start learning the piano. Adult beginners have their own problems, e.g. when to fit in practice, overcoming hang-ups about what they feel they should be able to do. It is best to come with no preconceived ideas and just enjoy every moment! At the moment I am not teaching adult students.