Why is there first blood fun in the name? Cuz you have quite a good chance to get it with this build. You just start at red, put 5 boxes there. At 1:40 you smite the biggest rave, and by the time you've killed red, you will be lvl 2. Everybody else on the map will be lvl 1, so it's the perfect oppurtunity to gank. Make sure you tell the midlane to let his/her opponent push a little, so your gank will succeed. Red buff will help you slow your target, so the first blood is almost certain.