The last step of setting everything up was really getting it settled in its final home. Behold our super fancy dust cover, which is just an upside-down Dollar Store bin.
We're using accordion-fold labels that self-feed pretty nicely, and those and the Raspberry Pi and the USB are all tidily bundled under the dust cover. We found early on that leaving the labels uncovered resulted in printing a lot of small blank spots which could interfere with the bar code. The $1 bin was the perfect size, keeps everything clean, and everything feeds underneath it nicely.
Of course, when we bundled everything tidily and set it up in its forever home, we had to unplug and replug everything. We waited about 5-10 minutes just to give everything a chance to boot and find each other again. I'm happy to report that a test page printed just fine! Be sure that your Raspberry Pi is configured to automatically log in, you can do this via command line or GUI (Menu -> Preferences -> Config).