Hatching and first few days of new chicks - female still in the box quite a lot. Male seen around and visiting the box much more. Both parents will go right inside the box to feed the tiny babies with small insects. Older chicks - parents visiting the box very frequently. They often don't go all the way into the box to feed.
Insects being brought are larger.
Parents will be seen carrying little white blobs out of the box - the fecal sacs. Fledging time approaching - nestlings will usually be seen looking out of the box for a day or two before fledging. Fledging - parents flying to and from the box, calling from perches nearby. Fledgling phase - parents may be seen carrying food to where the fledglings are well hidden in the trees. I am sure there is much more that can be added to this basic outline of mine by other listers.