Originally Posted by fawadhash

Number of books don't matter much. CSS, despite some misconceptions, is about smart and focused study. For 100 marks subject, usually 1 book is enough to cover all the topics like US history and psychology. For 200 marks subject, usually 2-3 books are needed, although you don't need to read entire books but selective topics. 8 hours starting now would be more than enough for preparation if its your first attempt.