Heidi Montag and Spencer Pratt
04/21/2009 AT 03:50 PM EDT
and Spencer Pratt have already had a casual, spur-of-the moment wedding in Mexico – but their weekend celebration in California will be more traditional.
The night before the ceremony
, which will take place on Saturday afternoon at the Westminster Presbyterian Church in Pasadena, Calif., the couple will hold a rehearsal dinner at Wolfgang Puck's Beverly Hills hotspot, Cut, a source tells PEOPLE.
It's a far cry from their Mexican wedding last November, which Pratt described at the time as having "margaritas, sunsets and beautiful settings" – but no friends or family. This time around, people close to the couple will be flying in to attend the festivities, say sources.
But it won't be all play for the reality star couple. The day before the
wedding, Montag, 22, and Pratt, 25, will be part of an NBC press day at the Langham, Huntington Hotel & Spa for the network's summer shows. The pair have joined the cast of I'm a Celebrity ... Get Me out of Here!
The reality series, set in the jungles of Costa Rica, will premiere June 1 and the full cast will be unveiled Friday. Among the names circulating are Duane "Dog the Bounty Hunter" Chapman and Idol
's Sanjaya Malakar.
Reporting by CYNTHIA WANG