According to a report made by CNBC and interviews with workers onsite, it seems that a date of when the Apple Retail Store will open have been given.
May 22, according to a personnel at the site. When spoken, confirming the date twice. There were rumors earlier on this month by a user also claiming of a opening date in May.
With several reports of an opening date in May and with ongoing works entering into final phrases, the Retail Store is definitely due for opening in May.
However, we can only take the news as a pinch of salt as there are currently no official or confirmation report from Apple in regard to the opening date.