Assuming you are working full time while preparing for the examination, you should allow yourself three to four weeks to read through the material and another two to four weeks to complete practice exams. You should attend the live class, watch the online video lectures or receive private instruction while you are reading the material or immediately after reading the material.
Proper prepartion, however, always varies from student to student, based on their background, ability to find study time, and general disposition for memorization and test-taking.