this is just my opinion, and I have been shooting a bow and bowhunting for 28 years,but I think that before you move back from 20 yds you should be shooting groups that all your arrows should be touching or at least very close to touching.You dont want to move back to soon because all you will do is hurt your confidence, and that is not a good thing for your consistancy. When you do start to move back to 30 and 40 yards and get proficient at those distances then that 20 yard shot seems like a chip shot