Ideally speaking, the right age is 7 years.
By this age, children mature enough mentally and physically. Their body organs too are developed. Even if they want to pursue a career in dance, they get the proper span to learn, to develop, study all the major aspects of dance and start performing or conducting classes. The body is flexible at this age. To learn the dance as a hobby, one can start at any age. As long as you walk or move, you can definitely dance.
Dance also help to stay healthy and fit.

There are seven classical dance styles in india:

Kathak from North India,
Manipuri from Manipur,
Oddissi from Orissa,
Kathakali and Mohiniattam from Kerala,
Kuchipudi from Andhra pradesh and
Bharatnathyam from South India (Tamil Nadu).

All these dance styles have a religious tradition. They have been basically developed for offering puja to religious deities.

The costume in each style is different and associated with the region where the style originated from.
Kathak and Oddissi has North Indian music while other styles have South Indian music. All styles though have a religious base.

This is an art and thus involves a never ending learning process.

As you go on learning, you realise that this beautiful art form is impossible to learn completely in a life time and yet, to adopt the basics can take at least a minimum of five to seven years, to learn. If you desire to undergo a certificate course, there are different institutes that offer different packages.

The All India Gandharva Mahavidyalaya University student, for example, has to
undergo seven levels of examinations to acquire a "Nritya Visharad", a degree equivalent to Bachelor of Arts. If the student wishes, she can take a gap before proceeding to complete the two-year Post Graduation.

The University of Pune, in the meanwhile offers a two-year Diploma and a two-year Degree Course. One can opt for either.

The Western ballet is based on a two or three beat cycle while the Indian dance is based on the concept of "Taal."

The "Taal" is a rhythmic cycle of definite beats of 8, 10, 12, etc. Costumes and jewelry hold significant importance in this Indian art form. This is not so in the Western dance. Indian dances can be performed solo which is not the case with ballet.

Another interesting difference is the absence of any footwear on an Indian classical dancer's feet, since we believe the dance is an offering of obeisance to God and not merely a form of entertainment.

It is the happiness of the soul.