It's never too early to celebrate a birthday!
E! News has learned the festivities took place at The Nice Guy in West Hollywood, Calif., Friday night from 9 p.m. all the way to 2 a.m. A source called the evening "very private" with just a few BFFs and family members present.
Some attendees documented the celebration on Instagram with the hashtag #OMGigi. With a little searching, it appears Cody's sister, Alli Simpson, along with Gigi's brother, Anwar Hadid, and dad, Mohamed Hadid, were all in attendance.