First mention of Paris Hilton in People Magazine:

September 11, 2000
In its' Insider column, People wrote that "Terminator 2's Edward Furlong was spotted hanging out with hotel heiress Paris Hilton at Las Palmas, an L.A. supper club."
Source: People, 9/11/2000

Photo: Florian Schroiff (2007 flickr)
First mention of Paris Hilton in gossip columns:

March 18, 2000
On March 18, 2000, The Express and various other English newspapers reported that Leonardo DiCaprio was seen in New York with "an 18-year-old blonde named Paris Hilton (THAT'S THE GIRL'S NAME!)." A friend of Paris' was quoted as saying: "What she really wants more than anything is to marry Leo."
Source: The Express, 3/18/2000

  New York Post reports that Paris was seen "engaged in full-blown passion" with the lead singer from Lit while in Cancun:

March 22, 2000

Source: New York Post, 3/22/2000

  Eric Clapton and Patti Boyd file for divorce:

April 29, 1988
"We will remain good friends and always be in touch", Clapton was quoted as saying in People Magazine.
Source: AP, 4/29/1988