I have a young man, whom just turned 20 yrs old in the 47 course with me. He came straight from HS, gets picked on a bit(mainly by instructors, playfully) but has thick skin as well. Finished 1st in his common core class as well.
I was gonna mention him too, I went through WOCS with him. Great guy.
It's absolutely possible to be successful through WOFT even with the age difference, but as Dmurray said, it takes thick skin. You're going to be in an environment where you're surrounded by type-A personalities, many of whom have several years of experience in the Army already.
That said, it's not inexperience that will make you have a bad time here - it's a lack of willingness to learn and to accept criticism. The ability to recognize what you don't know and then seek out help is your most important asset going through WOFT.