updated 10/15/2012 AT 4:00 PM ET
•originally published 10/15/2012 AT 5:00 PM ET
Witherspoon – who is also mom to Ava, 13, and Deacon, who turns 9 this month – looked casual and comfortable in a black top, jeans and sunglasses as she stepped out on Monday in Santa Monica, Calif.
Toth, 42, and Witherspoon, 36, couldn’t be happier to welcome the new addition home.
“Everyone is bonding with the baby,” a source told PEOPLE earlier this month.
Especially first-time father, Toth: “Jim has had a lighter workload and has been spending a lot of time at home with the baby at well,” the source adds.
Says a family friend: “He was just over the moon and really excited to become a dad.”