It depends on the individual. I passed 3/3 and had no background in finance (either in college or as part of work experience), but it helped that I had a strong math background. Other people with strong finance backgrounds and 3/3 record could start as late as February and make it. Below is how I did it:
I started in August, reading through the CFAI books (I skipped volume 1) and highlighting. I finished about a book every four weeks at a fairly relaxed pace, making sure I understood everything. I did blue-box questions to fortify concepts. This brought me to about January.
In January, I started reviewing and making notes. This process went a lot quicker because I had already highlighted everything. I also made flashcards I could study on the train to work. After making notes on a chapter I woud do EOC questions, which further solidified the concepts. I finished this process in about April.
From end of April to the exam, I did as many exams questions, and revisted EOC question and blue-box questions of concepts that I got wrong in answering questions. Also, studied flashcards on way to work.
Don’t underestimate the power of home-made flashcards. I once had a lady stare at me on the train platform, and when I noticed her staring she said that she didn’t know people still use flashcards.