Hello yuvashree

It's never too late to start.

You can start right now if you are ready to denote your time towards the studies. You have to devote atleast 10-12 hours a day if haven't started anything yet. Ncert is good for getting concepts but I suggest after completing ncert you for other books as well specially for maths as maths require a lot of practice.

For accountancy, you can rely on your textbook.

All the best!!