Camden, 6 next month, is the first of Nick and Vanessa's three children to head off to kindergarten
Credit: Nick Lachey/Instagram

The hardest thing Nick Lachey might have to do? Watch his little boy grow up so quickly.

On Wednesday, the 98 Degrees frontman and wife Vanessa Lachey saw their oldest child — son Camden John, who turns 6 next month — off to his first day of kindergarten.

Sharing a series of photographs presumably taken by Vanessa, Nick, 44, posed with a smiley Camden while the latter wore a sports-themed backpack and a blue-and-khaki school uniform.

The second image showed the father-son pair sharing a sweet smooch, while the third featured a cringing Camden adorably pushing his dad’s face away.

“My high & low for today: my son’s first day of [kindergarten], definitely a HIGH! Apparently also my last day for public kisses. Swipe ➡️😩 #proudpapa,” Nick wrote on the post.

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Credit: Nick Lachey/Instagram

Nick and Camden Lachey

Credit: Vanessa Lachey/Instagram

Camden Lachey

Mom Vanessa couldn’t help sharing her own tribute to her little boy as he went off to begin his new academic adventure, posting a photo of herself hugging Camden and a second of him posing next to a sign that read, “Camden’s 1st day of kindergarten,” alongside the date.

“It’s official, my first born is now off to his first day of Kindergarten,” Vanessa, 37, began her lengthy caption. “I’ll never forget our first skin to skin, his first hiccup, his first social smile, his first word (Dog), his first joke, his first ‘I Love You, Mama’ and now his first day of school. I still have so much to look forward to, his first serious question, his first girlfriend, his first time driving, his first broken heart (she better watch out!), his first day on his own in the real world and the first time he realized how we did it ALL for him and he says ‘Thank You.’ ”

“Even if he doesn’t, I am so proud of this little guy and can’t wait to see the man he will become,” the mom of three added. “Camden John Lachey, the world is your oyster! To the moon and back and back again!!! Forever & Always … my baby boy!!! 💫❤️💋”

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Ahead of Camden’s first day of school, the family of five (which also includes the spouses’ son Phoenix Robert, 20 months, and daughter Brooklyn Elisabeth, 3½) enjoyed a sunny vacation together.

“Soaking up the last few days of freedom before Kindergarten & Pre-School!!!” Vanessa captioned a photo of Camden with his arm around his little sister. “These two are going to be trouble in high school together … I can feel it! ❤️”

Alongside a snapshot of their entire brood, she wrote, “Missing THIS! Take us back! 🤪❤️ #SundayFunday blues … “