Update 01/13/2020 7:44pm:

According to Mitch Lawrence of SiriusXM NBA Radio, Zion Williamson is scheduled to make his NBA debut on Thursday against the Utah Jazz. Just a few weeks ago reports surfaced that the Pelicans were eyeing a January debut for Williamson and it appears the team is more confident in sticking with that goal.

However, Will Guillory of The Athletic cautioned NBA fans that the Pelicans haven't officially circled Thursday night's game. Guillory tweeted on Monday that there “still isn’t a planned date in mind”  and that the team is looking to squeeze in one more 5-on-5 practice before sending Williamson out there in official action. 

Original 12/31/2019 7:34pm:

According to reports, the New Orleans Pelicans are looking "hopeful" that Zion Williamson will make his NBA debut sometime in January. NBA insider Shams Charania broke the story, reporting that "both sides are hopeful of a January season debut for (Zion) Williamson.” It was reported last week that Williamson was being taught to walk and run differently, but apparently, the Pels feel he made the necessary adjustments. 

Source: bleacherreport.com