Mandy Moore and This Is Us Creator Mark the 'Last First Day' on Set as Season 6 Production Starts

This Is Us has kicked off production on the sixth and final season.

On Thursday, Mandy Moore was back to work on the set of the NBC series and shared photos from day one on her Instagram Story. "And we're back. Day 1 season 6 This Is Us," she wrote on one of her photos, which showed her in character as matriarch Rebecca Pearson.

And in between filming, Moore was spending time with her son Gus. "Back at work and grateful to have little man with me," the mom of one captioned a selfie of herself breastfeeding the 6-month-old, whom she shares with her husband Taylor Goldsmith.

Also on Thursday, the show's creator Dan Fogelman marked the bittersweet day on Twitter. "Last first day. Feeling feelings. #ThisIsUs," he wrote along with a photo of a monitor that showed Moore and Milo Ventimiglia acting out a scene.

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Mandy Moore / Instagram

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Mandy Moore / Instagram

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The day before, executive producer Ken Olin shared on Twitter, "Tomorrow. Day 1. Season 6. @NBCThisisUs. I'm directing @MiloVentimiglia & @TheMandyMoore to begin our final season. My goal is to appreciate every single day of work this year. It's the best way I can think of to honor what an incredible experience doing this show this has been."

And on Thursday, Olin gave an update from set. "Dispatch from the set of @NBCThisisUs. Day 1. Season 6. @MiloVentimiglia & @TheMandyMoore have still got it. It's great to be back with our crew!!! I'll keep you posted," he tweeted.

After the season 5 finale in May, Fogelman told PEOPLE and other reporters about his excitement for Moore to show off her acting talents even more in the final season.

"A big one that we've always planned on diving into heavily next season is the courtship and coming together and then ultimate separation then coming back together of Rebecca and Miguel. It's a big storyline we have," he said.

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"Mandy is going to have a tremendously ambitious season next year as an actress. Obviously, as you're traversing this timeline, these timelines into the future and her character battling Alzheimer's, it's going to be quite a showcase for a young woman, who I've been beating the drum for a while, is doing something quite extraordinary on television. So that's a big storyline to come," Fogelman teased.

While the last season won't air until early 2022, the cast and creators may be looking forward to another big milestone for the show: the Emmy Awards.

This Is Us was nominated for outstanding drama series again after a two-year hiatus from the category, and actors Sterling K. Brown and Chris Sullivan earned individual acting nominations.

"The whole cast chain blew up, we're back in the mix," Sullivan, who plays Toby Damon, told PEOPLE about the cast's group texts after hearing about the nominations, which were presented by their costar Ron Cephas Jones.

"I'm just excited to see everyone again. I'm excited to gather the community. And hopefully do it in a safe and healthy fashion," Sullivan said. "I'm looking forward to getting some well-tested vaccinated hugs."

Season 6 will surely answer a lot of fan questions after several season cliffhangers, including Kate's second marriage, Kevin's love life, Randall's career in politics and the flashforwards of the Pearson family's future.