What is the best age to start learning piano for optimal skill development and proficiency?

The best age to start learning piano for optimal skill development and proficiency is generally considered to be between the ages of 5 and 7 years old. Starting at this age allows for the development of fine motor skills and cognitive abilities that are important for mastering the instrument. However, it is never too late to start learning the piano, and individuals of any age can still achieve proficiency with dedication and practice.