When it is?
At the close of the plague.
With humans actually moving between worlds instead of the early “copy,” transmit, and print, there comes a shortage of human habitable worlds. Terra forming becomes too expensive in terms of time and mass to support the need for new, clean worlds. Human factions begin human forming to make themselves compatible with more worlds. Some introduce cybernetic or bionic alterations, some resort to genetic modifications, and some turn to alien DNA integration. Some allow the AIs to redesign them, while others seek more control of their future selves, and others reject AI involvement all together. As the multitude of variations logarithmically increase, the AIs are expected to insure all shades and shapes of humanity remain in some sort of whole … even after the alteration insanity creeps into the processes.