ET has the latest...

With their wedding just hours away, ET breaks all-new ASHLEE SIMPSON and PETE WENTZ "I do" details! Sources tell us that it will be an evening wedding with approximately 150 guests. It will be a whimsical, fantasy-themed affair, which will, needless to say, have high security.

Meanwhile, the celebration already began Thursday night as Pete and his soon-to-be father-in-law JOE dined out together at Mr. Chow in Beverly Hills. A bachelor party perhaps?

Ashlee also got in on the fun, having a bachelorette party of her own, according to People. The singer and her gal pals celebrated her impending nuptials at the luxury lingerie store Kiki De Montparnasse.