In the majority of weddings I shoot I will generally be there from "getting ready" which is normally 2 to 3 hours before the ceremony. Mostly it will depend on the bride and if she'd like me there that early to capture that part of the day, and what myself and the couple decide to have done when we do the planning meeting before the wedding.
We'll look at the ceremony time then depending on the package purchased, we'll decide then how many hours I arrive before so that it then times in with the packaged hours to fit in first dance and some party photos.
Getting ready is a perfect time of the day for me to support you from the beginning, it helps your wedding party get to know me and see how I fit into the day, so I normally try to fit this in to most weddings.