Well, that's only as far as I checked, I could have gone further but stopped. After 12 years of archives I figure they have them all.
well I went back to 91 on comp.os.minix to find the famous Linux announcement easy enough:
Google Groups hosts an archive of Usenet posts dating back to May 1981. The earliest posts, which date from May 1981 to June 1991, were donated to Google by the University of Western Ontario with the help of David Wiseman and others, and were originally archived by Henry Spencer at the University of Toronto's Zoology department. The archives for late 1991 through early 1995 were provided by Kent Landfield from the NetNews CD series and JÃ¼rgen Christoffel from GMD. The archive of posts from March 1995 onward was started by the company DejaNews (later Deja), which was purchased by Google in February 2001. Google began archiving Usenet posts for itself starting in the second week of August 2000.