In the absolutely last moment, which I assume should be around two- two and half months before the exam, where board exam is not involved, you should keep in mind the following. There is and fats rule for a last three months JEE Main preparation plan, but these should be helpful.
- Finish the topics you are weak in by January end or mid of Feb at max. Do not keep putting away hard topics.
- If there is at all any topic that you are unable to understand, reach out to a teacher who can patiently explain the key points so that you can attempt questions easily.
- Do not delve into theoretical discussions with peer group in the last few months. It is best to study alone, if that suits you.
- Mathematics, Physics, Chemistry: Now is the time to jump into solving maximum number of questions. Practice, practice, and practice more questions. Aim at solving maximum questions correctly in the least amount of time. Many students, despite being good at theory or calculations, leave out simple questions because they could not manage time.
- Books: By now you must have done most questions in the most referred JEE books. If not, pick up one of each subject and solve the moderate - tough questions. In JEE Main, questions are usually in this difficulty range, and seldom too tough to handle. Focus on increasing your accuracy. Solving more questions is important, but more important is getting them right. Remember there is negative marking.
Most important: Don't set limits! We have seen students calculation "how much marks will I need to get admission in XYZ college?" Remember, that you must aim for doing your best. You can get the best college, even better than the ones you have thought about. So work hard and don't give up!