Can you take the SAT and the ACT early? How many times can you take it?

I'm only a freshman but our school has a program that shows our test scores and high school GPA's and stuff to all of the colleges. My sis is a sopre and she has already gotten a few college apps from this. She has only taken the Plan and PSAT and she is not as good of a student as me (strictly speaking academicaly). I wanted to take the SAT and ACT maybe next year to see how I score and to get the college apps. Can you take these tests early and redo them?