Adam Wiggins of Heroku has spun up a fire and forget charting service. I’m using it here. That chart shows the wait to get a license at the Watertown Dept. of Motor Vehicles here in Massachusetts. They have a take a number queuing system that posts the wait times for all their services on the web. The charting is rough around the edges. The wait times are in minutes, and the chart along the bottom is more readable than the main chart. The main chart apparently plots only a handful of random points as soon as more than a few points are in the range. Playing with the sliders on the bottom might help. If I was in more control I’d plot only the points and not the line. Here’s my Ruby code for doing the polling. I have a crontab that polls regularly when the office is open.
So far the answer is, show up first thing in the morning, when they open.