Does it really matter, what year(s) the story takes place? JKR was careful not to litter the books with too many pop culture references, which would have dated them (see the Shrek movies). Throw out the 1492 mention, and the story sounds like it could be present day, and it just as easily sounds like it could have taken place a hundred years ago, or a hundred years from now. It's really kind of a timeless story.