All the illegals get probationary legal status immediately. As I understand it, the only thing that is “triggered” is the creation of the new indefinitely renewable Z visa. The probationary status means you get a “floppy card” that allows you only to work and not travel. The card that goes with the Z visa will be fancier and allow you to work and travel. But the bottom line is that once you have the probationary status, you are legal, which is effectively an amnesty.