11:28 AM PT -- Sources at the wedding tell us the Montage is crawling with huge celebs, we're told Kylie Jenner, Travis Scott, Usher, Ed Sheeran, Jaden Smith and the Baldwin brothers are all there ... not to mention a TON of models.
As for those pissed off hotel guests ... we're told JB & HB rented out nearly the entire hotel, leaving only about 3 rooms. Our source says those guests are now happy ... maybe a last-minute invite?
Justin and Hailey Bieber are hours away from hearing wedding bells in South Carolina, but they got the good vibes fired up Sunday night with some fun on the water.
A select group of the Biebers' wedding guests hopped on boats and headed over to the rehearsal dinner at the Montage Palmetto Bluff ... and their family and friends make up a pretty star-studded affair.
The rehearsal peeps included Justin's dad, Jeremy, and his family, Hailey's dad, Stephen, along with Uncle Billy and Chynna Phillips ... and famous friends like Kendall Jenner, Justine Skye and Fai Khadra.
Everyone looked stylish and happy -- enjoying a boat cocktail will do that -- as they arrived for the shindig.
As for the big day Monday ... we got some of the details ... the fun will get started at 6 PM with pre-ceremony beverages. Then, everyone will move to the Somerset Chapel for the ceremony before the party really gets going at the Wilson Ballroom.
A plated dinner will be served at 8 PM for 154 wedding guests, and the reception's scheduled to last until midnight.
As we told you, Daniel Caesar will be providing the music, and it looks like his band will be well taken care of too ... they get their own dinner buffet.
Originally Published -- 7:34 AM PT