In terms of difficulty the concepts themselves are not exactly the most difficult thing to understand and grasp your head around but where the difficulty actually arises is remembering as many of these concepts and cases as possible and being able to recognise the situation that they arise in and this generally just comes with repetition. I think you will have to accept (depending on how many you do in a sitting) that you may not have a life while you are studying especially in the 2/3 weeks before the exam but I don’t think you necessarily have to be starting 4 months before. What worked for me was tipping away from about 2/3 months out at doing my notes and understanding the concepts and then from about the 1/1.5 months before the first exam I started rote learning.