With 3400 the TPW is available, and it is is generally one week sometimes two weeks away. 3800 means the vehicle is assembled and the VIN is available. Once built it takes at least one week before leaving the plant, because of the paperwork that needs to be done and the time it takes for the dispatchers to set up the vehicles path to the dealer; plan on two or three weeks before it moves. Car haulers do not leave until fully loaded, whether truck or train car.
QC Hold is another story. There is no status code for it but more than one 4B00 is generally accepted as the indicator, but you will get at least one 4B00 before it moves so you definitely want to see one you just don't want to see several.
Once your VIN appears in GMConnects, try double clicking it, after a while the Window Sticker will come up. I print it out but I am compulsive about following this process. Once it comes up, movement is imminent, maybe even that day!
So if you are built say January 30, you will probably see your Window Sticker around the 12th, and if your dealer is close to the plant, see your vehicle a few days after the Window Sticker appears.
These are guesses. This retail buyer ordering process is not amenable to hard rules. I compare this process to an e-ticket ride, with all the twists and turns and ups and downs of the best roller coaster ride you have ever experienced. Enjoy the ride.
Laborsmith