Our Father's always told us on the weights," If you take them off too soon, You can always put them back on for a while later. It is hard to raise the horns up if you leave them on too long." We think the same basic theory applies to horn sloping. If you do them too soon when the horns are too light they are more apt too turn down too much. If you do them later it just takes longer for the horn to turn but surely less chance of " over doing it". We slope our horns at 14-15 mos and take about 1/3rd of the horn on the top side. Each individual is different. Heaviness of horn, degree up and degree back. It is a bit of a trial and error thing until you develop an eye for it. It sure helps to mark the horn with a magic marker before you pull animals head to one side. Helps you get the angle and amount more nearly the same. We still believe in the angle cut. Some people do not.