Pre-model 29s in the S147xxx range shipped as early as January 1956 (S1472xx shipped to Elmer Keith and was the fourth production gun shipped if I am quoting the S&WCA journal correctly) and as late as December 1957. Sorry for the wide range, but S&W did not ship serial numbers in order. You really need a factory letter to get the actual date.
Can you tell us more about it? Did it come with the original case, tools, etc? Condition? Inquiring minds want to know