So, since you are sure there were no "date-less" posters in this case, we added this:
"Note that starting around the 1970s, it was common for studios to print teaser and advance posters (which mentioned the date that the film would be released), as well as final theatrical posters which had no date because the film had been (or was soon to be) released. However, modern promotional campaigns sometimes lack a poster without a starting date, and the final theatrical poster is what we would normally call an "advance" poster. That is the case with the promotional campaign for this film, and this advance is actually the final theatrical poster created. However, for consistency, we are still calling this poster an advance."