The height of topping depends on tree size, vigor of soil, climate, variety, etc. Trees are nearly always whipped at planting. Save feathers only if plant spacing is close and trees are exceptionally large with at least three nice limbs coming out at wide crotch angles above the desired height for lowest limbs. Debud by removing 3-5 buds below terminal bud plus every other bud, but do this only with very large trees. Avoid removing any roots, unless damaged.
Large clothespins work better than standard pins.
Delaying beyond this time will limit the ability to improve the crotch angle. Select 4-6 scaffolds with wide crotch angles. Remove upright limbs with narrow crotch angles with a horizontal cut that leaves the bud at the base of the limbs. This cut will generally stimulate a branch to form during the coming season at this point that will naturally form a wide crotch angle. This includes removing buds on either side of the terminal bud if the terminal was not headed.