The May SAT is extremely popular among juniors since scores arrive later in the month and allow plenty of time to study and retake the exam in the fall if needed. If you're hoping to take the May 4th test, you need to act soon. The regular registration deadline has come and gone, but you can register late online up through the end of the day on Monday, April 22th. Just go to the College Board's SAT Registration webpage to sign up. Note that you'll need to pay at $27 late fee on top of the regular $50 exam fee.