speaking truthfully and by expeience of my own
i would like to say you that you should take such things upon yourself
i would rather say that you can end up in IIT Bombay provided you are enough serious and a intelligent boy to study on your own.
self study is the best studying experience but things doesnt happen as you expect. There are so many topics in JEE syllabus which are to hard to understand. so i would say that you should think carefully before taking such decisions. I was under the same state previous year so i made my mind to focus properly on 12th boards and get some time to study for jee simultaneously, i did my boards pretty well but my i failed to qualify for jee advanced just by 3 marks [ 81 was the cut off and i got 78] so i decided to take a year gap to focus again on jee on my own, Now I realized that I should have taken a guidance. im not sure about getting in IIT but im very much sure about getting into NITs . In short i would like to say that you can do self study for getting into IIT provided you are capable enough to understand the things on your own. Also selection of Proper books is an important thing so be carefull about it. Dont waste time as i know you have 16 months which is quite sufficient . Develop hard working nature, If possible get coaching from good institute if possible, Be patient and never get demotivated, Studying on your own for JEE will be hard amd that too without any guidance will make you suffer from regret. Think thrice before you take decision. Craking Jee by self study is not impossible task but not an easy one too.