[Astronomy]

Reinforcing collective wisdom... definitely go to Ranger School before SFAS. Naturally, with a generous physical recovery/trainup period between the two. You need to be at the peak of your physical game for both.

You'll find that having met the challenge of Hooah School goes a long way towards mentally mastering that later SF challenge. Different places, but similar conditioning, fortitude, teamwork, and no-quit attitude required. It won't make SFAS easier, but it also won't be your first gut-check rodeo.

Attempt SF after you've got some Junior NCO Troop Leading Time under your belt. That deeper well of experience will pay off later.