Photo: Tristan Thompson/Instagram

Tristan Thompson

Tristan Thompsonis celebrating a special milestone in his oldest child’s life.

The NBA star shared a photo on Instagram in which he poses with 5½-year-old sonPrince Oliverfor his first day of school on Tuesday

“My young King’s first day👑✏️📚,” he captioned the sweet father-son shot.

Thompson wore a Supreme t-shirt and black pants with printed Nike sneakers for the occasion, while Prince wore a Moschino t-shirt and a pair of army green shorts, By his feet was a Grogu-print backpack with his name on the front.

Thompson shares Prince with his ex-girlfriend, modelJordan Craig. He also shares an infant son and daughterTrue, 4, with exKhloé Kardashianand sonTheo, 9 months, withMaralee Nichols.

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Last month, the NBA pro, 31, took to the court with Prince, sharing a photo of the future All-Star wearing his dad’sChicago Bullsjersey while he showed off his athletic prowess.

“Training Day,” Thompson wrote on his Instagram Story.

“Starting them early,” the proud dad captioned a follow-up clip of his son practicing his dribbling.

tristan thompson/instagram

tristan thompson

Though he has yet to comment on his now 5-week-old son with Kardashian, a source told PEOPLE last month thatThe Kardashiansstar, 38, wanted to maintain the co-parenting relationship.

A source previously told PEOPLE, “Khloé and Tristan are not back together.”

source: people.com