They had already announced an opening date for Hagrid though so it's a bit different. With Bourne, it basically opens whenever they want it to.I remember the screen in Hagrid's queue, didn't stop them letting the GP in.
FWIW, i've heard that they understaffed on the ops side of things and that's causing issues as they plan to do continuous shows (supposedly), but ops had only prepared enough staff for what they would need for a set schedule.