Jessica Biel and Justin Timberlake attend the 2011 Vanity Fair Oscar Party Hosted by Graydon Carter at the Sunset Tower Hotel on February 27, 2011 in West Hollywood, California. Credit: Kevin Mazur/

This party has officially started!

On Wednesday, husband-and-wife-to-beJustin Timberlake and Jessica Biel hosted over 50 guests in Puglia, Italy for a pre-wedding beach party dinner, Us Weekly can report.

Casually-clad revelers, including Timberlake's "D--k in a Box" costar Andy Samberg and music manager Johnny Wright, arrived at Cala Masciola beach on the Adriatic Sea around 8:30 p.m. Despite the brisk temperatures, the crowd enjoyed dinner and cocktails at the beachfront setting, which was decorated with lanterns; music played throughout the festivities, including Marvin Gaye's "Let's Get It On."

At about 9:30 p.m., the crowd was treated to an impressive, 10-minute fireworks display -- and about an hour later, the group returned to the exclusive resort where the nuptials are set to take place imminently.

As Us Weekly revealed exclusively on Wednesday, the actress, 30, and Timberlake, 31, have finally chosen the southern Italy venue to tie the knot this week -- taking "extra precautions" to keep the location and details top-secret. Pals like Timbaland and Biel's Seventh Heaven costar Beverley Mitchell (who herself wed in Italy) were among the guests who were flown in for the biggest wedding of fall 2012.

"They are ready to get married!" an insider told Us.