Kelly, who is regarded as the Padres' No. 4 prospect according to MLB.com, has been working his way back from Tommy John surgery that he had on April 2, 2013.
Kelly will likely begin his rehabilitation assignment with Class A Advanced Lake Elsinore, located about one hour north of San Diego.
Kelly's rehabilitation from Tommy John surgery has gone relatively well and with few hiccups along the way.
He was scheduled to throw to live hitters on April 5 but told the organization that his elbow was a little sore. But he resumed pitching a few days later.
Kelly hasn't pitched in a real game since making a start for the Padres on Sept. 27, 2012, against the Dodgers.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.