Type your keyword into google and check out the first result?
I'll give you the benefit of the doubt here and assume you mean "first" as in chronologically, in which case I have no clue. Maybe the wayback machine.
shows articles on the day that Jobs died. blekko uses the date on the page as the date something was published, which means that we can't tell you anything that precise... most dates on the Internet don't have a timezone. Sorry.
Google uses they date they crawled something as the date for date sorting purposes. In this case that strategy might get you the answer you're looking for.