Bushtits nest

Here are two photos of the nest. One (slightly in shade) was taken just after the wind storm and shows some damage from those winds. The second photo (taken this morning and in bright sun at the moment) shows a more solid, repaired nest which just may be inhabited already.
It's hard to know when the birds "move in". There is no address sign set out. The nest is completed; the eggs are laid; the parents sit on the eggs until they hatch and then work like mad to protect and feed the chicks until they fledge. Two years ago, we noticed that there was vague motion of the bottom of the nest/sack. A short time later, we saw increased activity from the parents flying in and out of the nest and saw 3 little open mouths peering out of the nest opening for a few seconds after a parental departure. We continued watching as much as possible but missed the chicks fledging a few weeks later. One day, the nest was empty! That was all. This year I will try to be more vigilant without being intrusive. Since the nest is so very clearly seen from our window, it should be much easier.