"They wanted to have it before his tour," the source reveals. "It's going to be a small, intimate wedding."
The couple, who got engaged December 2011 after four years of dating, are planning the wedding at Lake Como, a beautiful Italian lake town. (The breathtaking European location is a favorite of George Clooney, who owns a home there, as well as Channing Tatum and wife Jenna Dewan Tatum.)
In October, the Sports Illustrated model, 27, told Us that she already found her wedding dress! "I'm doing Vera [Wang]. There's nothing like putting on a Vera. The difference is so amazing. You feel like a princess," she said.
Of her nine-time Grammy Award winner fiance, 34, she added: "John thinks that I'm going to wear something super sexy and fitted, but he has no idea!"
The "Ordinary People" singer's tour goes on break from Aug. 17 to Oct. 20, when he's due to perform at Foxwoods in CT.