Dear aspirant,

Do what you dream! The decision rest on you because you have decide whether you want to prepare for jee advanced solely or have a college seat. If you have target of IIT B CSE then you should try to achieve it.

Now coming to question is it achievable in 9 months or not?

Surely, it can be if worked hard with consistency and patience. Regular learning theory, practicing question, giving and reviewing test will help a lot to improve. Solve Previous years question for better understanding of exam in last 1-2 months.