Want to become a JEE maths teacher

I am currently pursuing MTech CSE from an IIT (3rd gen IIT) and have realised that I don't want to join IT instead I want to become a JEE maths teacher. I have given JEE attempt three times in 2016,2017 and 2018.How many months will it take to cover whole JEE maths from GB sir maths videos available on telegram, considering that I also want to over CBSE Maths NCERTs first from class 7 to class 12. How many months will it take to become capable enough to at least start teaching JEE Maths students? And where can I get a job as a fresher? My ultimate aim is to open my own JEE maths coaching. Any kind of suggestions will be deeply appreciated.