Son, current junior took it end of Sophomore year after several months of self study to get a good baseline. Landed a 1490 so able to breath a little easier, will take the ACT in December and plans to take the SAT two more times in Spring. Taking it early worked well for him, as it is one less thing for him to stress about going forward.

Kid got a prep book and took 2 or 3 practice tests before taking the SAT fall of junior year.

Agree-- don't really see why you'd take it cold once when you can just take the practice tests.

Junior DS taking a prep class now and will take SAT for the first time in December. If he wants to improve after that, may do some private tutoring and retake in Spring.