What's the Right Age to Start Lessons?

I have been teaching music to all ages, zero to adult, for over 22 years and I get asked this question often.  What is the right age to start lessons?  Well, it depends what you mean by "lesson"?  I started formal lessons at age 8, but prior to that I had been nurtured by my two grandmothers whenever I would visit their houses on the weekends.  They would give me time on the piano with them and by the time I entered formal lessons I was well into the 2nd level of piano books.  
So what is meant by "lessons" then?  There are formal traditional lessons where the goal is to learn how to play an instrument through reading music.  These lessons usually begin alongside of proficient reading skills in school between ages 5 and 6.   There are informal musical experiences such as Music Together, Kindermusik, Music Garden and many other programs that immerse children ages zero to five in a musical environment with no expectations about their performance or understanding.  Then there are semi-formal experiences like Music Monkeys and Music Mind Games which teach specific musical concepts like tempo, dynamics, rhythm, tone without the pressure of having to perform a specific piece of music the next week.  Finally, there are Suzuki beginning lessons where students as young as three years of age are taught specific skills on their chosen instrument that are repeated in small units of focus until they are mastered.  One thing that is clear--there is a large body of research suggesting that if children are not introduced to music-making skills before age 9, they may lose the skills to become musically competent in the future.  I hope this helps those who have this question.  In the Suzuki Piano Academy, students can begin piano lessons as early as age three.  It is common to start Suzuki piano lessons anywhere between ages three and five years of age.  Other Suzuki instruments may vary depending on the instrument of choice and the teacher's preference.  For instance, some Suzuki guitar studios prefer waiting till the hand has grown more and must delay until age 5 or 7.  Since the piano is a percussion instrument and I use a very vertical approach to playing with the arm, it is easy for a very young child to execute a good tone on the piano.