Despite the general ambiguity of the timeline, if I remember right there was a reference to the date during Nearly Headless Nick's 500th Deathday where his death was said to be 1492, putting the current date at 1992 (in the second book anyways).
. . . I just realised how sad I must look for remembering that :/
As for the films, it's mainly implied by the background, though I guess it could be taken either way.