Another Store Event Question

Does Bill always put the year that he signed a piece? I have a few pieces that I purchased from other dealers and they seem to all have the year that he signd them. I also have a few with Nancy's signiture,she seems to put month, date and year. would it be a good idea to get Bill's also and then maybe Kims some day on the same Piece?

Bill nearly always puts the year that he signs on the lighthouses.. 99.9% of the time!