The Church begins the practice of abstaining from meat at the age of 14 (canon 1252) but does not place an age limit on the practice. The only exception would be for medical or health reasons.
As for whether you are required to abstain from meat on all Fridays of the year would depend on where you live. In the USA and many western countries the obligation to abstain from meat is only for Fridays of Lent, on other Fridays of the year Catholics in those countries can substitute another form of penance.
