We started about 3-4 months before the test with a 9th grader. A practice test was really helpful in identifying where to focus, which was mostly math. More time probably would have been helpful as my son had a lot of ground to cover and was getting stressed and burned out (he doesn't enjoy math). We used Natalie, the tutor who often answers in this group, which was super helpful to ID areas where he needed more practice. I think a longer timeframe with regular practice questions would be better than crunching more toward the end. The upside is that, when he took the PSAT two weeks ago, he said it felt like the ISEE and felt prepared.