In reply to El Cap:
I take the view that you should:
a) always be tied into the rope.
b) have at least two points of attachment to the system.
My system is:
Get to lower-off and clip a 1.2m sling (with a screwgate either end) between harness and one bolt (the lower one if there are two). A daisy chain of quick-draws clips between harness and the other bolt.
Pull up a bight of rope and pass this through (both) bolts.
Tie a figure of eight knot in this bight and attach to belay point of harness with a screwgate.
Untie the end of the rope and pull through the bolts.
Retie the end of the rope into the harness. (You may not need to do this if it is a short pitch but if you have a 60m rope and the pitch is 30m....)
Undo the knot on the bight of rope.
Haul up on the belay and get your second to take in so that you can feel the rope pulling at your harness.
Unclip from the bolts and lower away.
The advantages of this are that, 1. at the point at which you untie from the end of the rope you are still tied in but the rope is already through the belay and attached back to your harness. 2. While you are doing the re-threading, you have three other attachment points to the system.
Things like this are a bit difficult to describe in text only so have a play around at low level if possible.
HTH
Bob