Expect to hear Gov. Sarah Palin answer her first mainstream media questions shortly after 6:30pmET on Thursday this week.

Confirmed last night, ABC News' Charlie Gibson was picked by the McCain campaign to conduct the first interview with Palin, and today we learned more details of how it happened and what the interview will entail.

We hear from insiders that Gibson was informed he was the Palin choice just after leaving Friday night's live World News broadcast from Los Angeles. In fact, he was supposed to immediately go take publicity photos with the other two evening news anchors involved in the Stand up To Cancer special, Katie Couric and Brian Williams, but we hear he kept the duo waiting while he discussed the interview for 10-15 minutes with the McCain campaign.

Over the weekend, details were set. Gibson will interview Palin in several locations in Alaska on Wednesday and Thursday and Friday, and the interview will air in parts beginning with World News Thursday night, Nightline later and Good Morning America Friday morning.

"There were lots of negotiations in terms of what and when and how," said World News EP Jon Banner, but he says there are, "no preconditions," as to what can be asked.

Gibson was slated to ride the train this morning (more on that later), but he missed the trip because, as ABC News president David Westin said, he is "busy cramming" for the interview.

"The time change is a challenge to say the least," said Banner. "But it'll be fun."

• Related: The World News staff requests questions for Palin from readers on his World Newser blog.