It struck me last week that instead of picking a "school's out" date, we can use a different method to determine when we're done for the year. I assessed the remainder of the work that I felt we should finish and made a checklist with each page/chapter/lesson (depending on the subject) typed into a small table. This checklist fits on one page, and will allow Finn to see how much he has left to do before school has ended. We originally planned to end on June 17, but now Finn has the freedom to do as much as he wants and finish ahead of time--which I suggest, because otherwise he'll have to take schoolwork on his road trip next week!
A good friend of mine who was homeschooled (and who doesn't school by date, but by when they're done with their books) has noted that when she went to college she was amazed at how the students who had attended school seemed to procrastinate their work, dragging things out until the bitter end, whereas she was used to just getting it done and getting on with her life. I think this is a good trait to cultivate!