[Brennen81]

Early June 2020 is when the new Tahoe, Yukon and Escalade will arrive according to a GM spokesperson.

"We can deliver on our commitment to near-term launches like our full-size SUVs and getting parts to our dealers," Barra said. "In Arlington, we completed the buildout of the previous generation SUVs and the plant conversion for all our new models. We will begin shipping the first units to dealers in early June."
GM Posts Q1 Profit as Crosstown Rivals Ford and FCA Report Losses - MotorTrend

 

[Brennen81]

UPDATE

A new GM memo confirmed when exactly production plants in the U.S. and Canada will restart:

“GM plans to begin a limited, cadenced, and site-specific approach for a return to the workplace in many of our North American manufacturing facilities. We are targeting Monday, May 18, and we are collaborating with state governments and union partners. We are confident that we have an approach that allows us to move into this next phase with safety as our guide.”