I'm assuming you are using some cheap loads. I'd start with a 1/8 rotation and see what that gets you. If you still have the sight adjustment disk then you can slide that on the screwdriver for a more accurate adjustment. Personally I throw it in the trash and just take an uneducated guess. Less is more most of the time. After 1 or 2 adjustments you'll have a feel for how much to turn it to get it where you want it.
Just make sure you get those lock screws on the back loosened about 1/2 turn before you make any adjustments. You will need to tighten them back up before firing another shot.
An alternate way of doing it is to fire a shot on target. Set your gun on your rest with your dot centered on the middle of your target (not the center of the pattern). Then adjust your dot until it is centered on the middle of your pattern. Again, your gun must not move once you start moving the dot. The nice thing about this is that the adjustments are smooth and easy to turn so just setting your gun on any rest should prevent the gun from moving. Once you loosen the lock screws you won't be torquing anything with much pressure at all. Then tighten your lock screws and you're done. Fire for effect and you should be good to go.