George Clooney and Amal Alamuddin have already started the celebrations.
"The Monuments Men" actor/director and his new fiancee toasted to their engagement with a party at Cafe Habana in Malibu on Sunday, according to several reports.
"George seemed sweet with his fiancee," an onlooker told Us. "I saw them kiss once, and he had his arm around her the majority of the time. They looked very happy."
The group congregated on the restaurant's patio, did some karaoke and toasted to the couple with wine and tequila, People said.
It seemed to be a relaxed affair, with the 36-year-old bride-to-be wearing a glittery neon tank top paired with floral shorts and a blazer and Clooney sporting a casual blue polo with jeans.
News that the "Argo" producer popped the question surfaced late last month.