I had four chickadees fledges in early May from the first birdhouses I ever put up. :)
Now we have a Carolina wren’s nest with four newly laid eggs in it. We also have a newly built house wren nest (whole) in a different birdhouse.
Mine fledged early last week from the bird house I installed on the side of my house which I could observe thru the garden window over my sink.
As a side note, after they fledged last year about the same time, another pair immediately took up residence.......