The clock is ticking, the event-planners are bustling and maybe, just maybe, a fetus is growing.

After saying their respective farewells to the single life on Thursday night—which, aw, ended with the duo recoupling at the Roosevelt Hotel—Ashlee Simpson and Pete Wentz are primed to swap vows sometime Saturday.

Sources once placed the nuptials at a friend's house in the tony beachside town of La Jolla, Calif., but now all signs are pointing to a Valleyfied affair at parents Joe and Tina Simpson's Encino home.

Party preparations started taking place Thursday as Simpson family employees, an SUV full of balloons—and, at one point, Jessica Simpson herself—were spotted bustling in and out of the Royal Oaks Colony, the gated community where Joe and Tina live.

And, thanks to telephoto lens-toting paparazzi, a tent was spied going up in their spacious backyard.

E! News learned today that a truck from Jackson Shrub Supply (a longtime supplier for the film and TV industry) delivered urns, sod, sandbags and array of foliage, including California ivy, privets (clusters of white flowers), Eugenia (a common ornamental plant that can sprout fresh fruit), ligustrum hedges in planters and ball-shaped topiaries. All is supposed to be picked up Monday morning.

And that's not all the greenery—a pair of pickup trucks towing biodiesel generators showed up at 10:54 a.m.

Here's a glimpse of the Royal Oaks action:

Also this morning, another truck delivering sound equipment was admitted through the gate and—perhaps in rejection mode—a blue BMW full of orchids, gardenias and other flower arrangements was seen leaving the area.

Workers from Unique Tabletop Rentals exited the gate at 3:44 p.m., presumably after setting up a host of tables.

Meanwhile, a source said that, if not a wedding, at least a prewedding "gathering," such as a Friday rehearsal dinner, would be taking place at Casa Simpson.

—Reporting by Matt Donnelly, Whitney English, Jeanifer Hwang and Claudia Rosenbaum