JM, stock is in the middle position. Rotate the stator clock-wise to the next mark is advanced, rotate the stator counter-clock-wise to the next mark is retarded.
K5, best thing I can tell you is try retarding it and then try advancing it. You should be able to tell which works better for you. Maybe stock setting will be best. There are mixed feeling on whats BEST. Only you will know with your machine and riding style.