"They are both beyond ready to be parents," says a Kutcher insider. "They've been talking about having children for nearly a year. They are so excited for that next step."
Kunis, 30, and Kutcher, 36, who became engaged earlier this year, are gearing up for a big 2014.
"I think they'll be traditional and get married before the baby is born," the insider says. "Ashton wants this marriage and relationship to be perfect."
The laid-back couple, who hammed it up for the kiss cam at last Saturday's L.A. Clippers game, began dating in 2012 after Kutcher's split from Demi Moore, 51, in 2011.
"I am so happy for them," says a source who has worked with Kunis. "They've been together for a while. This is what they wanted and they will have a beautiful baby. I think they are both ready to be parents. I think they’ll be great parents."
For much more on the couple's pregnancy news and Mila's upcoming appearance on Two and a Half Men, pick up the latest issue of PEOPLE, on newsstands Friday/
With reporting by AILI NAHAS and K.C. BAKER