100%. Now, if we were to go back 50 years when the only way to take a practice test was to sign up for a real test date and take a real test, maybe, but there is no need for the time machine. Every test prep company I know offers this as a first step. And when you have a decent score, stop!
For a lot of students, getting this done before junior year can help with the timeline, but that generally works best for students who already have enough math. (Many do, btw) If you need to learn the math to take the test, you’ll be better off learning it in school and delaying testing.