Rumer Willis Talks 'Excitement' for Baby Daughter Louetta's First Christmas: 'I Can't Wait' (Exclusive)

Rumer Willis is counting down the days until her first Christmas as a mom!

The actress, who welcomed daughter Louetta Isley with boyfriend Derek Richard Thomas in April, opened up about her excitement over the upcoming holiday during the opening night of Love Actually Live in Beverly Hills, California, on Wednesday.

“Oh, it's the best,” Rumer, 35, exclusively tells PEOPLE of having a new addition to the family during the Christmas season. “We haven't had a baby in the house in so long."

"So to be able to have that kind of Christmas energy and our first Christmas with my family — all of us there with a new baby, and having that joy and excitement of Christmas, I can't wait," she adds.

As for festive preparations, the new mom already has them well underway.

“I think I bought little Christmas onesies before she was even born,” Rumer jokes on the red carpet at The Wallis Annenberg Center for the Performing Arts.

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But little Louetta won’t be the only member of the family sporting a Christmas outfit, as the Sorority Row star says that the entire extended Willis clan dresses up for the holidays.

“We always do the matching pajamas every year, all of us,” Rumer says, adding that she’d love to establish some Christmas traditions of her own now that she’s a mom.

“I love that there's a possibility of being able to do new traditions as well as carry on the old ones that we've already had,” she adds.

Rumer also reveals to PEOPLE how her 7-month-old daughter reminds her of her movie-star father.

“Whenever she's got a stern discerning look on her face, I just see Bruce Willis,” she says. “My dad — especially on [TV series] Moonlighting — has this little side smirk, that very [mischievous] twinkle in his eye, and I see that so much in her.”

The oldest child of Bruce, 68, and ex-wife Demi Moore — who also share daughters Scout and Tallulah Willis — goes on to share that becoming a mom is “incredible.”

“[Louetta] is truly the joy of my life and my little best friend, and I've never had anything happen to me that's brought me greater joy,” Rumer tells PEOPLE.

The Once Upon a Time ... in Hollywood actress and musician boyfriend Thomas, 29, welcomed their first baby together on April 18, announcing the news in a joint Instagram post. 

"✨ Louetta Isley Thomas Willis ✨ You are pure magic 🌱 Born at home on Tuesday, April 18th," the proud parents wrote alongside a sweet photo of their newborn daughter. "You are more than we ever dreamed of ✨."