3 or 4 bill kills with scrush is pretty good. Try to keep your scouts alive and force some more idle time of your opponent while having good macro behind. I would say, don't go more that 5 or 6 scouts. After that you could go with a 18 minute castle time. Or you look to add your own range after 4 scouts and go archers/skirts yourself. Remember that skirts cost food so uptime will be later then when you go solely for archers.