Dating Butterick patterns accurately can be a complete nightmare because they seldom printed dates on their envelopes. McCall’s, on the other hand, dated pretty much everything; you get the impression McCall’s was staffed entirely by the kind of people who should not be left unsupervised with a label maker…
If you’re interested in narrowing down a date range beyond a particular decade, Wade Laboissonniere’s books (Blueprints of Fashion: Home Sewing Patterns of the 1940s
and Blueprints of Fashion: Home Sewing Patterns of the 1950s)
are considered vintage pattern bibles, but they only cover the 40s and 50s in depth. Other options include consulting vintage pattern seller Cemetarian’s awesome pattern dating pages or (this is probably the most fun option) snatching up vintage pattern catalogs when they finally emerge from people’s attics.
In addition to the lists of current pattern numbers in each catalog, sometimes the advertisements yield clues that can help narrow down a date range. The inside back cover of this Butterick Back to School pattern catalog from 1952 highlights how the style of notches printed on their patterns had recently changed.
If the diamond shaped notch had only recently come to Butterick patterns in 1952, patterns with the old style notch (pictured) stand a good chance of being made in or before 1952.