Her plan was to draw him out of the house and into her trap. One of Qetesh's pets was tossing rocks at the house, making soft pinging sounds that would hopefully get him to come out and see what was going on. The rest were well hidden so that if he looked out the window, he wouldn't see them and they could get the drop on him.
This would be her biggest and best score. With the Colonel at her side, Qetesh felt like she would be able to take out those nasty Winchester boys and that wannabe soldier boy, leaving her as the force to be reckoned with in this town.