Kim Kardashian hasn't wasted any time since Kris Humphries popped the question in May.
"We obviously move really fast in my family," Khloe told Us Weekly during the NIVEA Challenge in Bel Air, Calif. Sunday. "We're so crazy busy, and Kris was going back to Minnesota to be with his family. We were trying to find a day where the two fiancees could be there with all of us. On Monday, we realized that Thursday was open, so I was like, 'Am I really going to throw a party on Thursday?'"
To help organize the get-together, Khloe called upon party planner Sharon Sachs, who oversaw the E! star's wedding to Lamar Odom in 2009.
"She did my wedding in nine days, so I was like, 'You can put together an engagement party in three days!'" Khloe laughed. "It was really fun."
Nearly 50 close friends and family members attended the celebration, including several friends who hadn't yet met the New Jersey Nets player, 26.
"Everybody had the best time and got along," Khloe told Us. "It was so sweet see everyone hang out with each other."
The following night, the family flew to Las Vegas to celebrate Khloe's birthday at Sugar Factory American Brasserie and Chateau Nightclub & Gardens.
"We're excited about having downtime," Khloe told Us of her summer plans. "We're excited to do normal family stuff with no cameras documenting it."