There is no time limit for acquiring knowledge. I can show you thousands of lawyers in Lucknow and Kanpur who have not attained the knowledge beyond POA, Caste Certificate, Gun License, succession certificate etc and they even cannot face the Court clerk in the Court.
It depends what actually one wants one school says that initially every lawyer should give at least ten years to the profession and thereafter there will be no looking back.
Other school says that initially one puts at least three years in District Court to know the procedure and basic drafting, then at least five years in High Court to know drafting, court craft legal research client handling, corporate litigation etc. It's like whatever we sow that's what we reap.
All the very best in all your professional endeavours.