New mom Hailey Bieber has already brought her baby boy, Jack Blues Bieber, along on an important tradition.

On Thursday, Oct. 31, the model and Rhode founder posted her first picture of her infant son, since she and her husband Justin Bieber welcomed their first child in August. She shared an adorable Instagram Story featuring a close-up of the baby’s tiny legs while sitting in a gray car set.

In the sweet pic, young Jack is getting in the spirit—not for Halloween but for the upcoming election. Rather than sporting a pintsized Halloween costume, he’s dressed in a bright magenta onesie with an “I Voted” sticker on one foot.

“Happy Halloween! Get out there and vote,” Bieber wrote in an added caption.

On August 23, Justin Bieber announced the baby’s birth by posting a photo on Instagram of Jack’s newborn feet and his wife’s hand (sporting one of her signature manicures). “WELCOME HOME,” the singer wrote in the caption, before sharing his son’s name. “JACK BLUES BIEBER.”

Hailey later re-shared his post to her Instagram Stories, adding a teddy bear and a tiny blue heart.

The recent “I Voted” sticker shot is only the second shot the couple has shared of their newborn since his big debut.

In a PEOPLE interview shortly after the Biebers welcomed their firstborn, a source close to the pop star confirmed that the couple was "overjoyed" with new parents.

"The baby is such a miracle. He's adorable and doing well," the source said. "The pregnancy was something that they very much wished and prayed for. The day they found out that Hailey was pregnant was the best ever for Justin. He was over the moon with excitement. It was a big celebration for them."