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The last big Kardashian wedding was nearly two years ago -- when Khloe wed Lamar Odom in L.A. in late September 2009.

With Kim Kardashian and Kris Humphries tying the knot in less than three days (!), what does Khloe, 27, advise for her big sister?

"It's not about having everything perfect!" Khloe told Us Weekly at Wednesday night's launch bash for the Kardashian Kollection at Colony in Hollywood. (The entire clan turned out for the bash: Kim and her fiance Humphries, Kourtney Kardashian, mom Kris Jennner and siblings Kendall and Kylie Jenner.)

PHOTOS: See more pictures of the Kardashian Kollection's launch from PopSugar

Although Kim is set to wear a $25,000 Vera Wang gown, chow down on a $20,000 cake and greet such A-list guests as invitees Nicole Richie and Ryan Seacrest, Khloe says Kim's priority on August 20 should be her man, 26.

"At some point in your wedding, take your husband in a corner and just be quiet and look and enjoy the whole presence of it," Khloe said. "And just look and enjoy because it goes so's amazing."

And once the wedding and honeymoon are over, and Kim settles into normal life? "No two relationships are the same," she said. "Keep yours to yourself because everyone will have an opinion. They have no idea what goes on behind closed doors."

And the bride-to-be herself is doing just fine during the final wedding countdown, she told Us. "I'm totally calm," Kim said.

"I'm just really looking forward to the whole wedding." And she and her groom are rock-solid, she added. "We have a really good balancing system of, you know, our personalities. [Kris] lets me chill. He gives me my space when I need to design and approve shoes and clothes and everything, and I kind of do the same for him. We just have a good connection."