JAM

Hello
First of all, you need to know the IIT JAM SYLLABUS & exam pattern. As early as you know syllabus and exams pattern, you can start preparing a few months before exams. You don't need to cover the whole syllabus. But whatever she is good at, you should study those things very well and clear all the doubts and concepts of that topic. As far as my concern I had studied everything except electronics and statistical mechanics ( because in my personal opinion I found it boring). I had studied only some of the specific topics of electronics. You should try more and more questions. You can solve at least the previous 5 years question papers of IIT JAM of physics. You should select a chapter wise book for jam questions paper because after studying a specific topic, you can solve its questions. You must take at least 2 - 3 online mock test. Online test series will definitely help you in exams. For the online mock test, I selected a career Endeavour test. But you can also select any of test series for IIT JAM Physics. Check https://scoop.eduncle.com/iit-jam-physics
During exams, Don't try to waste too much time on a single question. Every question is important.