I really think he starts in Harrisburg and is promoted to AAA by Memorial Day. I am guessing that the FO mind set is still he needs to learn the OF and there is no reason to rush him no matter how well he does offensively.
Given that he does start slowly why put that added pressure on him. He has already played for Harrisburg and there shouldn't be a big adjustment after ST. Just my take on it. If he tears it up at Syracuse then I could see a promotion to the show before September but everything is contingent on what he achieves not on our hopes and expectations.