"Officially" May 5th with the press event, but they have been running previews for Cast members, AP holders and DVC members, so I would expect that on your trip you should be able to catch it open. "Soft openings" are done prior to official opening, basically what that means is it may or may not be open through the day, it can close at anytime and reopen at anytime, there is no schedule, it is basically a test and adjust period where they are tweaking for the grand opening. Since you will be there the week before the official opening you should be able to catch it open. Of course there is no Guarantee, but keep your fingers crossed.