John Stamos Posts Sweet Photo Of 4-Year-Old Son Billy Starting School: Trying ‘Not To Cry’

John Stamos’ mini-me is growing up right before his eyes! The “Full House” alum took to Instagram to share a sweet pic of the father-son duo smiling together while donning matching white, short-sleeved shirts to mark a very special milestone for his 4-year-old son Billy. “One of us is starting his first day at school. And the other is doing everything in his power not to cry,” John wrote.