Ashlee Simpson and Pete Wentz will wed Saturday, May 17 at a "top secret" location, a source close to the couple told Usmagazine.com.

"Proper invites have not been sent out but instead guests have been given a save the date notice," the source told Us.

The rehearsal dinner – described by the source as "an intimate affair" for "family and close friends only" – will take place on Friday.

On Saturday, "all guests will be transported in shuttles to the wedding location," the source explained.

Simpson, 23, and Wentz, 28, announced their engagement in April.

Usmagazine.com broke news that Simpson is pregnant with the couple's first child.