Take this example:

    with click.progressbar(length=6, label="Doing something") as bar:
        for thing in [3, 2, 1]:
            time.sleep(thing)
            bar.update(thing)

This shows nothing until three seconds, at which point it shows:

Doing something  [##################------------------]   50%  00:00:03

Would it be reasonable for it to display a 0% at first?
This is mostly an issue with a small number of items which take a long time.