LSAT Teacher, Founder of LSATdemon
Consider rescheduling your exam if you have the opportunity. For tests like the LSAT, one night is not enough to study. If you take the test cold or you prep with only a week or two, you're not going to score as high as you could. You really need about 3 months to study for a test like that, so if you don't have enough time to prepare, you should reschedule it.