AAA, first man up.
If he's tearing the cover off the ball, he'll force the big league team to make room for him.
At the risk of sounding like Joe Maddon or a crazy man that thinks Luis Robert needs to stay in AAA, Schwarber was drafted as a catcher. If Collins really forces the issue, they'll teach/cram him in at 3rd as a backup, like they did Yermin, or left, like the Cubs did with Schwarber.
He could also force out one of McCann or EE, which could be amazing or terrible depending on circumstance.