Seven-time Tour de France champ Lance Armstrong, 34, moves fast – even when it comes to planning his nuptials with new fiancée Sheryl Crow, 43 (in New York City on Sept. 27). A spring wedding is already in the works, Crow tells PEOPLE. And what type of celebration does the first-time bride want? "Don't know yet," the singer says. "I think probably a pretty big do."