The couple, who secretly exchanged vows at a civil courthouse ceremony in September, are still finalizing details for a religious ceremony and reception.
"They've been figuring out the perfect time to do it, and they both feel like the sooner, the better," a source close to Bieber says in this week's issue of People. "They're still figuring it out."
The singer, 24, and the model, 22, initially eyed a January bash but will likely push to a later month.
"They're working with the schedules of all their friends and family to make sure they can be surrounded by the people they love," adds the source. "There's no real rush. They're already legally married, but they're very excited about throwing a celebration with their loved ones."
Bieber and Baldwin's ongoing wedding planning comes on the heels of a romantic New Year's trip to Oahu.
The once on-and-off couple—who previously dated before a messy 2016 breakup—rekindled their relationship this summer, before Bieber proposed to Baldwin in the Bahamas on July 7. Just two months after his proposal, the pair quietly tied the knot on Sept. 13 in a New York City civil service.
At the time, an insider told People: "They're going to have a big blowout, in front of God and everyone they love."