Yes, but not once it is bugged. Then you can go on with your business or wait for hours. Been there, tried that.
Maybe the trick is really not to hide or never to be in hide when the script triggers (like with some other quests that spawn mobs and they will be instantly resetted to their first spawn point and stop moving to the target...so the assasins might appear anywhere, just not near the player). This might be a reason why i mainly had troubles with this quests on rogues.