I'd wait at least one full summer before applying to new asphalt. The coal tar emulsifications are the best. They are blacker, last longer, and are not so affected by gas and oil spills. They are also cheaper, usually. However, they contain quite a lot of VOCs which supposedly cause cancer. Because of this, coal tar emulsifications have been made illegal in a lot of areas. In these areas you're stuck with some sort of asphalt emulsification, which just isn't as good. They are a dark gray color, last only a few years regardless of what the manufacturer will tell you, and gas and oil will dissolve them. Additives make them more resistant to gas and oil, but they are still not as good as the coal tar. So if coal tar is still available in your area, that’s the way to go.