Timing is everything.

Katherine Heigl** and husband Josh Kelley always planned to have more kids after adopting daughter Naleigh from South Korea in 2009, but they figured another child was still a few years down the line. So it was a shock, to say the least, when the actress got a call earlier this year saying that she could have a baby within the month.

On Thursday, Dec. 20, the 34-year-old mom-of-two opened up to Tonight Show host Jay Leno about her unexpected second bundle of joy, Adalaide Marie Hope, whom she and Kelley adopted in April from a woman in Louisiana.

"This was fascinating, because we started the adoption process again and we thought we were gonna adopt internationally. It's a pretty long process. It can take years," the former Grey's Anatomy star explained. "And then we started exploring because we had heard that Korea had gotten very hard to adopt from, and China had a very, very long waiting list...And so we started exploring the idea of domestic adoption -- just exploring -- and then my lawyer called and said, 'There's a birth mother, and she's due in four weeks, and she's all yours if you want her.'"

Heigl definitely wanted her -- but her singer-songwriter husband of five years needed a little convincing.

"I had to talk Josh into that one," she said, laughing. "He thought it was gonna be a few years, and that we were gonna end up with more of like a 9-month-old or 10-month-old, and he looked at me and said, 'You're telling me [that] in a month we're gonna have a newborn?' And I said, 'Yeah, it's perfect timing, don't you think? Look, we're both here, we're not working. This is great. We can spend time with her."

"It actually has been beautifully serendipitous and graceful, because we've gotten to spend all this wonderful time with her," Heigl gushed.

Indeed, even 4-year-old Naleigh has bonded with the tot.

"She is loving being a big sister!" a source told Us Weekly earlier this year of the couple and their kids. "Everyone is doing great. They're thrilled to add to the family."

This article originally appeared on Usmagazine.com: Katherine Heigl: I Had to Talk Husband Josh Kelley Into Adopting Second Daughter Adalaide