According to Gerd Schraner's "The Art of Wheelbuilding", after inserting the trailing keyspoke(the keyspoke is right next to the valve hole), count off 8 holes in the hub and insert one leading spoke and thread it too the second spot opposite the valve hole.
My keyspoke is the first one you see on the left.
After three spokes, the hub is stable and placed pretty much where it should be.