Hey there

The best time to prepare for jee is from 11th. You have enough time if you start preparing from 11th. So for jee coaching is important honestly. You can use online video lectures also in case you can't afford offline coaching or if you belongs to a remote area where good coaching is not available. Then just divide your day for physics, chemistry, maths and study all 3 every day. Consistency in study is the key of success.

Check detailed tips for jee preparation

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/how-crack-jee-tips-from-experts-and-toppers/amp&ved=2ahUKEwixpuTN6a7lAhWWfCsKHV9xBY4QFjABegQIDhAH&usg=AOvVaw0VR3liwI7Ltck1WZHgyg8Z&ampcf=1

Good luck