Hey Alok !! 

You can really complete one chapter a day with your class 12 course. Choose one chapter of any subject , read your course book , NCERT , solve previous year questions for the same chapter , and further assignments or booklets if available with you. But for that u need to see the weightage of every class 11th chapter ... Question trends and you are good to go. 

But remember REVISION is what is important, coming back to all the chapters u have studied in a week , revising the chapters and make sure you solve one complete test paper every week , just to know which all chapters you are strong at.. It doesn't matter whether you have completed the course or not ... Sitting for 3 hours and practicing questions is important and will definitely help. At the end READ NCERT THOROUGHLY IF YOU WANT TO CLICK NEET. NCERT BIOLOGY CHEMISTRY IS IMPORTANT.