Do I mount the trim ring before mounting the wallplate for the Lyric thermostat?

The trim ring and wallplate are designed to snap together prior to mounting to the wall. Align the screw holes and snap the trim ring and wallplate together before screwing them to the wall. Note: The trim ring is an optional accessory that you can use to cover blemishes such as holes or gaps in the paint or wallpaper left by the old thermostat. If you choose not to use the trim ring, you can mount the Lyric thermostat directly to the wall without it.