Fredrik Eklund Shares 'Bittersweet' Message About His 2½-Year-Old Twins' First Day of School

Fredrik Eklund is having mixed feelings about his twins starting their academic journey.

The Million Dollar Listing New York star and husband Derek Kaplan posed with son Fredrik "Freddy" Jr. and daughter Milla in front of their Los Angeles home on Monday, before the 2½-year-olds headed off on their first day of school.

"It's a big day when your kids start school. Like bittersweet. Time just flies, they grow up so quickly," Eklund, 43, began the caption on his post, which also featured snapshots of the twins separately and one of them checking out some toys, presumably at their new learning center.

"I mean it was yesterday I bathed them in the kitchen sink," the father of two recalled. "Today they wore their little backpacks and held hands visiting their first school and meeting the teachers and new friends. Somehow I could see into the not so far future and them graduating."

"It's inevitable — and [exciting] — but all so soon. ☺️," Eklund concluded.

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Last week, PEOPLE got an exclusive first look at the first two episodes of Eklund's new YouTube children’s show, Freddy and Milla's Adventures. The series sees the Swedish real-estate mogul homeschooling his kids while touring jaw-dropping properties around the world.

Each episode focuses on a new lesson, from the ABCs to learning about emotions, set against the backdrop of various lavish listings — including the first-ever tour inside Eklund and Kaplan's new homes. The first two episodes also put the recent New York City transplant's home on the West Coast — a sprawling estate in Bel Air — on display.

"This is something I've been thinking about for a long time," Eklund told PEOPLE of the story behind the show. "I've been sharing a lot about the kids even before they were born — some of the struggles, from the miscarriages and surrogates to the experience of becoming a dad — I put myself and family and my emotions out there a lot, so the steps to create a format around this came naturally."

Staying home with his kids during the coronavirus (COVID-19) pandemic also influenced him, he explained: "Of course, in the lockdown, while schools in California are closed and all the parents around me and my clients are homeschooling [their kids], I just thought, I'm going to take this into my own hands."

RELATED VIDEO: Million Dollar Listing New York's Fredrik Eklund Moves to Los Angeles with Family

Eklund explained that he wanted to create a show that would be educational and entertaining to both kids and their parents, pairing playful graphics and sound effects with tours of aspirational properties and sprinkling in some surprise celebrity cameos for good measure.

"I've been watching a lot of YouTube videos since [the twins] were born, kids' shows," said the Bravo star. "I pick what they watch, I sit with them and watch through it … I just thought, there aren't any series that show a parent interacting with their child in the show, and no one is doing the real-estate perspective."

Regardless of whether the show yields new clients, Eklund is grateful for the experience, telling PEOPLE it has been "really fun to record."

"Just spending time with [the twins] is amazing, and being able to mix my work and having them understand a little bit of what I do while also having a lot of fun," he said. "For me, the worst that could happen with this is that no one watches the show, but I've still had an amazing day with my kids and had a lot of fun."

You can catch new episodes of Freddy and Milla's Adventures every Thursday on YouTube.