Is the Army Slit option only for high school juniors?

Im a senior in high school and have already joined the U.S Army Reserve component. I have yet to ship to BCT until this July. College is very important, so I was thinking if i could do the slit option. I talk to my recruiter and he told me that this option is only for high school juniors. On the other hand, I heard this option is also available for college students. So was my recruiter wrong? and if he was, can I chose a slit-op even thou i signed my contract?