The notches on the rear wheel adjusters are to get you into a ball park area.
As Dazco mentioned, The proper way to adjust a rear wheel is to measure from the center point of the axle to the center point of the swing arm pivot on both sides. Once you have the proper tension on the bottom rung of the chain, make sure these two measurements are equal to each other.
If you have never done this type of adjustment procedure before, your labor time should be one beer. Steve

:-D