Historically top students (high CSU GPA) that are invited to apply to the Honors college, some OOS/International applicants and local SD students that participate in the Compact for success program have been admitted early. Although there are always other applicants that fit these categories which are not admitted until March.
For the Honors college, all applicants can apply even in not invited but the early admits have a priority deadline.
Unfortunately, SDSU admissions is not transparent on whom they admit early and the criteria.