Hello,
IIT JAM is one of the toughest exams conducted in India. So, prepare yourself well for it.
JAM Exam will be on 10th Feb 2019. So, from now you should only study the important topics of JAM Mathematics.
Start solving previous year IIT JAM Question Papers and online mock tests. This will give you an idea about the pattern and difficulty level of the questions.
You must study at least 6-7 hours and give your last 30-45 mins to the revision daily.
Learn all the formulas and make notes of them.
Best of Luck!