I think for NEET final year would be ideal. But that is if you have studied in your first years. I mean you should’ve been a regular reader at least. That’ll make it easy to start with coachings in the final year. 2 years are more than enough to crack NEET PG.
BUT, I cannot be sure for NEXT. I have no idea how the exam will be and if they take an exam just after final year, you should start from 3rd year then.
Actually the portions can be completed in a year. I studied only during my internship for Pg and cracked it. Duties and studies together are hectic but not impossible. But that was possible may be because I’ve always been a hardworking student since first year. I topped all four University exams. I am not bragging. I’m giving you an example to compare your position with.
If you start in the third year with DAMS/marrow/prepladder, try to finish the third year subjects and the minor subjects of final year like Anaesthesia, ortho, radio, skin, psychiatry in the third year. I mean, watch all the videos. Qbank isn’t that important right now. This will make it easier to pass the 3rd proff and also complete a lot of the syllabus. Then you can do the remaining subjects of final year in the final year itself and the subjects of first two years can be finished in the first half of internship (by MAY I think). After that you can revise all the 19 subjects from June to Dec almost 3–4 times well.