I've brought this up before because, well, the anniversary for her X-Men Evolution episode is coming up. So we know that's August 2nd(just 23 days away!). There's also secondary dates of importance though with X-23 too.
While her first appearance to the world was through X-Men Evolution on TV, her first appearance to the Marvel world on the printed comic page was December 10th, 2003. This same pattern tends to prove true for a lot of comic characters that begin through one form of media and then traverse back to the original comics their parent company was founded with. Be it DC or Marvel, or any other that have traveled from on the screen to on the page. Whether it's a Firestar that's born, or Chloe Sullivan investigating Clark Kent; they all started somewhere.
So here are some of the key dates that matter for X-23 so far. These are the surface level details and dates. They do not entirely reflect her pivotal story issues and their dates. That list will be coming soon as I continue going back over the old issues and do more digging still.
August 2nd, 2003 is the air date of her first X-Men Evolution episode. This is when American children first met her through KidsWB. It was the 11th episode of the 3rd season(episode 41 over the entire series) and called "X-23." The follow up to her story is in the 46th episode of X-Men Evolution's run(season 4, episode 3) called "Target X." It aired originally on August 30th, 2003.
December 10th, 2003 with NYX issue 3 is her first appearance in the Marvel 616 universe. A story known to others as "NYX: Wannabes."
First official meeting with the X-Men was on October 6th, 2004 with Uncanny X-Men issue 450. This was part 1 of the 2 part story "The Cruelest Cut."
She joined her first official team, the New X-Men from Academy X, with their issue 20 released on November 9th, 2005. This was part 1 of the story "Childhood's End."
January 12th, 2005 is the date of her first issue of her first self-titled miniseries with the release of X-23v1 issue 1. It was part 1 of 6 to her "Innocence Lost" story.
On October 11th, 2006 issue 31 of New X-Men hit shelves. This featured the first appearance of Kimura, the Sabertooth to X-23's Wolverine. It is part 4 of 4 to the story called "Nimrod" from the pages of New X-Men.
September 15th, 2010 is when the first issue of her self-titled ongoing series was released. It was part 1 of "The Killing Dream."
December 14th, 2011 is when Laura first officially entered the Avengers-in-training ranks of the Avengers Academy with issue 23 of that series. The story was called "Second Chances."