You should plan to install a faceplate in a very late stage of its development, most likely after painting it. The reason for this is that you wouldn't want to spend money (And it today's economy that's harder to do nowadays) on a faceplate and ruin it with bondo, resin, or paint because you installed it too early. Then again, you could install it, then cover it with masking tape or the like, but it is much easier when resining and other good stuff.