May my student leave early if they have completed the test?

This depends upon whether your student is taking the SSAT at Home, Prometric SSAT, or paper-based SSAT. For any paper-based SSAT, given testing in a room with other test takers, the student may not move ahead early or leave early. For the SSAT at Home and Prometric SSAT a student is testing individually and on their own appointment and may end sections early, move to the next section, and end testing completely when done.