How difficult would it be to complete a marathon if you are not used to running?
The amount of reading required during the SAT may feel just like a mental marathon. Similarly, if you are not prepared, your brain will run out of energy. The more preparation for race/SAT day, the better you will perform.
Start now! No matter how young you are! Prep your brain by reading nonfiction. Pick up a magazine, such as
Read newspapers online. Grab a book about a topic that interests you from the library. You won't get up to speed overnight, so start reading nonfiction now!