For me, no two (musical) things herald the beginning of Christmas than hearing Nat King Cole and Arthur Fiedler and the Boston Pops. Of course, everyone knows Nat Cole and "The Christmas Song". The entire album is great and worth a pickup if you don't have it. My personal favorites are "God Rest Ye Merry Gentlemen", "I Saw Three Ships", and "A Cradle in Bethlehem".
From the Amazon bio: "Arthur Fiedler (December 17, 1894 - July 10, 1979) was the long-time conductor of the Boston Pops Orchestra, a symphony orchestra that specializes in popular and light classical music. With a combination of musicianship and showmanship, he made the Pops one of the best-known orchestras in the country." Nothing puts a smile on my face like the opening track of the Pops' "A Christmas Festival", which can be purchased from Amazon here. For your listening pleasure, I've embedded it below.