Where did the time go?

Giuliana Rancic's husband, Bill Rancic, took to Instagram on Friday, June 3 to share a precious new photo of their son, Duke — and we can't get over how big their boy has gotten!

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How happy is he???!!!!!

A post shared by Bill Rancic (@billrancic) on

"How happy is he?!" the 45-year-old entrepreneur captioned the sweet photo of the couple's three-year-old on his last day of preschool.

RELATED: Giuliana Rancic Talks Having Another Baby with Husband Bill Rancic — See What She Revealed!

Bill and the 41-year-old TV personality — who married in Capri, Italy in September 2007 — previously welcomed Duke, their only child, via surrogate in August 2012.

Click through the gallery below to see more celebrity kids then and now!