I don't know the link to historical park hours, but I have been to WDW during the very first week of January in 2000, 2001, 2002, and 2005. AK was always 9-5, MGM 9-7 or 8, Epcot 9-9, MK was usually 9-7, but one year it was 9-8, and a couple nights even 9-9.