Hey buddy, congrats on owning a .223... Now for your question...
Being that rifles will shoot ammo differently you can start at about 1 inch... However, you are misunderstanding the meaning of the trajectory calculations by Hornady... When it says zeroed at 200 yards it means just that, you need to zero it at 200 yards to be precise. To do this correctly you need to go somewhere you can safely shoot 200 yards. Then set up a rest for your rifle that will allow you to shoot with no movement of the rifle. Pick a calm windless day to get it as close to the center bull as possible. Once you have achieved this you can use the Hornady trajectory guide as just that, a guide. When you are doing actual shooting you will still need to adjust for wind speed, direction and so on... Once you have your rifle zeroed the best thing to do is practice, practice and more practice... Hang in there and you'll get it... :gun2::yes: