Simran Vinaik
Set a schedule which help you to master Concepts of JEE syllabus in detail till December.
Most Importantly solve Questions connected with the concept you study everday.
Post December give time to revision of the things you covered .You may take doubt resolving sessions once a week of your doubts from us if you are doing self study.
In the last 3 months you must solve as many test series and mock tests as possible. This will help you avoid negative marking and give you variety of questions .Make sure that you give these tests regularly and that they are timed well.
For more info about subject preparation tips refer to the link.
https://www.askiitians.com/iit-jee/how-to-prepare-for-iit-jee.html