you don't have much time to prepare for competitive exams then first you think you should do is to remain stick to the syllabus in solve only those questions which are important from the point of view of exam and not find yourself in the trouble by solving other questions which are irrelevant to the exam next thing which you should do is to solve previous year questions because they are the key to success you can easily understand the pattern by solving the previous years question and you will get the ID of level of exam and as well as where do you stand right now. chemistry portion is relatively easier in both of the exam therefore you should try to maximize your score in Chemistry by solving all the problems in NCERT for physical chemistry and reading line by line for inorganic and organic. SinceSince you left with very few once there for you should solve very selected questions that is ddos which give you a new concept everyday and not to solve repeated questions this is also very important. If you are interested in cracking the examination span of time if you follow all about three points then there are good number of chances that you may be in the list of merit.