I still contend that when you see a crisply printed date disc on an early 1680 today it is a replacement, not an original. I had many conversations with Ubi at the time he produced the wheels and he was very sure of what he was doing and of the results. And I have seen pictures of early original 1680 wheels as well, and they are very similar.
This is not the best example by a long shot, but I can't seem to find better ones right now. Notice, though, how the 3 is not of uniform, consistent thickness and also a little bolder than the 0. Also notice a general lack of crispness, but again nothing compared to other examples I wish I had handy...