I love my Andis, you will need a #7FC blade as well. It comes with a #10 and looks like they are on sale at Petedge. The 10 you use on the face on the schnauzer, the 7 you can use on the body. It will take it down fairly short. For a cotton coated Schnauzer you will likely have to go fairly short anyway. A #5 will give you a slightly longer cut and a #4 longer still.
http://www.petedge.com/shopping/prod...67&itemID=6142