You should be doing self study for atleast 5-6 hours everyday where you study theory for atleast 1½ hours and then keep solving MCQs for the remaining time. Keep a goal for every day and try to solve atleast 100-150 MCQs during the starting days and keep on increasing the number gradually. Keep in mind, you'll only get good scores if you have a grip over MCQs. Devote more time to the subject that you are weak in and try to make it strong. You should be knowing all the concepts well. You should be done with everything till the end of 2019 so that you have enough time to work on your weak topics.

I don't quite understand what do you mean by mahe exam. If it's MAH-CET, then yes you can write it after NEET because it usually happens after NEET.