I wasn't really thinking and I started to do this activity with my 4-year old. The puzzle was way too easy for him the first time I cut it. I cut each piece in half again to make it harder, but by then he had lost interest. I am hanging onto it to pull out at a good time to try again.
So I tried again with my 2-year old and had great success. Well, I guess that depends on how you define success. He did not run off to spend lots of independent time working on and improving his puzzle skills. But we had a fun time playing together with a free and easy toy. He really liked watching me cut the puzzles, so he asked me to make one from all 6 sides of the box. Then, after spending a little time putting them together with him, he found an old plastic butter conatiner to store his new toy in, and carried it around a bit.