You can trade the draft rights to a player at any time you want...even months after the draft.
I don't think it really matters, though. I think the Jazz FO likely has the draft as Irving, Willaims, Knight. Despite working out solo - on the advice of his agent - I think Brandon helped himself yesterday. He's well-spoken, has a high BB IQ and was a model kid in HS. Character will NEVER be an issue with this kid. And I definitely think he could become the leader on the court the Jazz need. He can even play some 2 w/ Devin in a small line-up. Jazz will draft Harris #3...guaranteed.