That is correct. It can also be done after they graduate from high school. My son graduated HS, went to BCT over the summer for Army Reserves, and started college and ROTC this fall. He currently goes to drill weekends once a month, and will do AIT next summer.
We're also curious how this will affect an application to West Point, since my son is now looking at the Soldier Admission option. From what I found, as long as he's completed BCT, he is eligible (AIT is not a requirement.)