David Cavanagh has this as 12
November December 1968 in Good Night and Good Riddance. Perhaps because broadcast after midnight?
According to Ken Garner's The Peel Sessions book, the show was broadcast on 11 December 1968.
Apologies ... 12 DECEMBER 1968 in Cavanagh's book.
But indeed as I thought, the show was aired in the early hours of the 12th according to Beatles Bible .