You'll reach a saturation point when it's difficult to retain any more info. When you reach that point, you won't gain much from studying more. If you long to study something new, and studying just makes you frustrated, then it's probably time to take the test. You'll never be 100 percent ready. When you're at the saturation point, schedule the test appointment within one to two weeks. Don't chicken out on the date you've set unless you have a very good reason.