It hasn't been confirmed how many vials will drop per kill. So it could be the 2.1 (BT) version which lets everyone loot it. Therefore the launch IS Wednesday. If however it is the 2.0 version than you'd need 6 weeks of clears to have 24 people enter MH.
Thread: http://forum.warmane.com/showthread.php?t=366932
"The drops for The Vials of Eternity have been modified. Vashj’s and Kael’s Vial Remnants are now multi-drop quest items. This means they’ll be lootable by each raid member who is on the quest, as opposed to the four vials that drop at the moment."