BB - The 55 day thing that you mentioned is BUSINESS days, not CALENDAR days, which puts the latest day possible for the announcement way before June 28.
But I think that is more of a recommendation than a set (unbreakable) rule.
If that was a set rule, Thero would not have said that there is still a chance for an AdCom.
Somebody posted that the PDIFA date is also flexible. If they want an adcom sept. 1st the. The pdufa date then gets bumped the 55days. Not sure the truth to the post but just sayin. Please don't ask for a link