You can read through the
Frustrated thread, but MANY variables. It's expected to be about 10-12 weeks from order to delivery.
In my experience, after production, it goes through QC, called "Bayed" (3 weeks for me). Then it loads on a train (another 3 weeks from Arlington to Portland, OR). Then from train yard to dealer (5 days for me).
Also, in the event you don't know, you can go the GMC.com and on the right hand side is a CHAT link. There are good and average folks working behind the link. The good will dig deeper and provide detailed location of the vehicle.
Good luck and enjoy the ride.