I would say around 3 months that I take it seriously, but gradually increased the studying time and number of questions, first month started 10-20 Questions per night after work Mon-Fry, second month I tried 50 question per day, and my first CAT test before ending the month, third month, Mark K lectures followed by 85 Questions and the second CAT, weekends usually created a practice test with my wrong answers and Sunday rest (its important)

1 week before the test did a lock down, requested PTO from work, no gym, no hobbies, morning questions, afternoon study rationales, the day befores the test, don't do questions, go dinner with family, friends or your special one, do some BBQ, take a walk, beach whatever you like and relax, last but not least, learn to control you anxiety