<p>My son was valedictorian. At his school, they used the grades up to the last progress reporting period of his senior year. As you mentioned, though, this varies from school to school.</p>
<p>My school uses grades up to the very end of senior year, so the valedictorian could in theory change just a few days before the graduation ceremony.</p>
<p>OP, my son’s school has two progress report periods and then the final grades come out for the semester. I think the third progress reporting period ended toward the middle of May. He found out then he was valedictorian.</p>