On our trip to Quebec last year I bought a few French books at a bookstore. "La Planète des Singes" (The Planet of the Apes) was the shortest one (only 190 pages) and I started reading it sometime in November I think. I usually only read it while sitting at gymnastics or swim class. Since it was notable mental effort to read it worked well to focus on it in small doses. Instead of reading a few pages a minute I was reading a few minutes per page.
I was pleasantly surprised to find that I could understand probably 50-75% of the material. Enough that I followed the story line all the way through and could provide a high-level synopsis, but I definitely missed details and nuance. And I also learned several words by context. Some were pretty obvious: "gorille," "chimpanzé," "orang-outan." But others were less so, like "chaloupe," meaning "shuttle/skiff" which took them from their spaceship to the planet's surface.
Probably the most satisfying moment was near the beginning of the story when I determined the characters were discussing the time-dilation effects of general relativity. I figure I must be doing okay with my progress if I can identify general relativity being discussed in French.