Hello there!

Greetings!

I can understand your situation as I was in the same situation, during my time , first of all to cover the class 12th organic chemistry, you need to cover 11th ncert organic part at least  , there's no other way as 11th organic is the basis of your 12th organic and you cannot understand it in a proper way if you haven't studied 11th organic and believe me you have enough time for your boards just give 3 hours to class 11th organic each day and you will be able to complete it in 2 weeks and then it will take you another two weeks to 3 weeks for completing your class 12th organic, I had done the same and I scored 91 marks in my 12th chemistry exam ; you can do the same , you can take the help of Youtube and believe me , it will help you a lot in clearing your concepts and completing the syllabus on time, you can use youtube channels like keep educating yourself , arvind arora chemistry etc , I had used these channels personally, and then go through ncert and its exercise and once you are done with the syllabus,  don't forget to keep revising it as there are name reactions and all which require memorisation . Best of luck for your boards.

thankyou