http://forums.worldofwarcraft.com/threa ... ost8782552The event has the potential to last for a couple weeks, but depending on how voraciously your realm is fending off the invasion it may be finished a bit sooner. You can speak to the Argent Dawn stationed in all major cities for progress updates on how the war is progressing, and they may give some insight as to how far along you may be.
About the Length of Scourge Invasion
About the Length of Scourge Invasion
I ain't leaving without your soul and I am sober this time.