Timeline

1999

March 30, 2001 - The Nightmare Begins airs for the first time.
April 6, 2001 - Parent Teacher Night and Walk of Doom air for the first time.
April 13, 2001 - Bestest Friend and NanoZIM air for the first time.
April 20, 2001 - Germs and Dark Harvest air for the first time.
April 27, 2001 - Attack of the Saucer Morons and The Wettening air for the first time.
May 4, 2001 - Career Day and Battle-Dib air for the first time.
August 17, 2001 - A Room with a Moose and Hamstergeddon air for the first time.
August 24, 2001 - Invasion of the Idiot Dog Brain and Bad, Bad Rubber Piggy air for the first time.
August 31, 2001 - Planet Jackers and Rise of the Zitboy air for the first time.
September 7, 2001 - Plague of Babies and Bloaty's Pizza Hog air for the first time.
September 21, 2001 - Bolognius Maximus and Game Slave 2 air for the first time.
October 26, 2001 - Halloween Spectacular of Spooky Doom airs for the first time.

March 22, 2002 - Mysterious Mysteries and Future Dib air for the first time.
March 29, 2002 - Door to Door and FBI Warning of Doom air for the first time.
April 5, 2002 - Battle of the Planets airs for the first time.
April 12, 2002 - Abducted and The Sad, Sad Tale of Chickenfoot air for the first time.
April 26, 2002 - Megadoomer and Lice air for the first time.
May 10, 2002 - Tak: The Hideous New Girl airs for the first time.
May 24, 2002 - GIR Goes Crazy and Stuff and Dib's Wonderful Life of Doom air for the first time.
July 12, 2002 - Hobo 13 airs for the first time.
September 28, 2002 - Walk for your Lives airs for the first time.
December 10, 2002 - The Most Horrible X-mas Ever airs for the first time.

May 11, 2004 - The first Invader Zim DVD, Doom Doom Doom, is released.
August 31, 2004 - The second Invader Zim DVD, Progressive Stupidity, is released.
September 1, 2004 - IGN: An Interview with Jhonen Vasquez and Rikki Simons
November 21, 2004 - The third Invader Zim DVD, Horrible Holiday Cheer, is released.

June 10, 2006 - Backseat Drivers from Beyond the Stars airs for the first time in the United States.
June 17, 2006 - Mortos der Soulstealer and Zim Eats Waffles air for the first time in the United States.
July 15, 2006 - The Girl Who Cried Gnome and Dibship Rising air for the first time in the United States.
July 22, 2006 - Vindicated! and The Voting of the Doomed air for the first time in the United States.
August 12, 2006 - Gaz, Taster of Pork airs for the first time in the United States.
August 19, 2006 - The Frycook What Came from All that Space airs for the first time in the United States.

February 21, 2011 - Operation Doom is released
March 25-26, 2011 - The first InvaderCON takes place in Atlanta, Georgia
December 24, 2011 - The Pilot airs on television for the first time ever in the United States.

February 13, 2015 - Independant comic book publishing company Oni Press teases a possible Invader Zim comic book.
February 20, 2015 - Oni Press announces an Invader Zim comic book series.
May 23, 2015 - A 'zine' style Issue 0 is released.
July 8, 2015 - Issue 1 is released
August 19, 2015 - Issue 2 is released
September 16, 2015 - Issue 3 is released
October 14, 2015 - Issue 4 is released on print.
October 21, 2015 - Issue 4 is released digitally.
November 11, 2015 - Issue 5 is released on print.
December 2, 2015 - Issue 5 is released digitally.

February 15, 2017 - Issue 17 is released
April 4, 2017 - Nickelodeon officially announces an untitled Invader Zim television film is in the works, also confirming that series creator Jhonen Vasquez will be involved in the project.
April 5, 2017 - Issue 18 is released
May 10, 2017 - Issue 19 is released
June 14, 2017 - Issue 20 is released