https://www.cnet.com/news/this-is-verizons-first-5g-smartphone/

It turns out, the 5G Moto Mod will make the Moto Z3 the inaugural phone once Verizon turns on its mobile 5G service. A Samsung smartphone teased by Verizon and Qualcomm at the Snapdragon Tech Summit last month will be the second device. And while AT&T and Sprint have both said they will carry the Samsung phone too, Vestberg reaffirmed that it has an exclusive deal. That indicates the Samsung phone will likely come to Verizon first for an exclusive period before moving on to the other carriers. 

While Vestberg declined to comment on the exact timing of the launch, you can sketch out the potential window. It's widely anticipated that Samsung will launch a 5G variant of its Galaxy S10, which usually launches in late February around the Mobile World Congress trade show. Vestberg's comments indicate that the service and the 5G Moto Mod will launch before then.