If someone else is doing the Windsor quest that Squire Rowe starts, you'll get the following text from Rowe:

""Marshal Windsor has been expecting you, <name>. Unfortunately, he is currently indisposed. He should be returning shortly.""

The wait time while Windsor's being escorted by another player to Stormwind Keep is approximately 10 minutes.

BTW, you don't need a raid for this quest, as the quest text would lead you to believe. Just escort Windsor to Stormwind Keep, where he will call upon Lady Prestor, turning her into her true form, Onyxia. This spawns eight dragonkin guards. You don't need to bother with them -- Highlord Bolivar Fodragon, a level ?? boss, can easily take them all out himself. You need to just stand there and watch. Windsor will die, then Bolivar will give you a new quest -- ""The Dragon's Eye"" -- for which you'll need to find the dragon Emberseer in Dustwallow Marsh. And that's all there is to it.