The Drive's[1] reveal story is timestamped 13 January 2018 and says GM showed the 2019 Silverado to the public at the North American International Auto Show in Detroit; Wikipedia[2] gives the same formal unveiling date. A first appearance was held at Texas Motor Speedway the month before.
Chevrolet formally unveiled the fourth-generation 2019 Silverado 1500 at the Detroit auto show on 13 January 2018: up to 450 lb lighter with a 6.2L V8 and 10-speed automatic; prices were announced in June 2018 from $29,795.
$29.8K