The time span between when we find out about AGI and when an ASI pops up is likely very short, from instant to a few months. Because if you have three or four demonstrable AGI's there is a potential, perhaps likelihood, that one will step outside of the weak bounds we have placed and start hooking itself up to multiple data centers and multiple AGI models to build a composition that is beyond a human-level general intelligence. Even 2X human intelligence is "super" and there is little limit other than thermodynamic laws on that multiplication factor if left unchecked.
ASI should be truly terrifying. A machine that can't realistically be debated because it has considered a thousand variations of an argument before you have finished stating it. It won't actually need any human to double check it or control it. The lack of autonomy in current agents is likely temporary, and we'll see sub-AGI models doing all sorts of terrible things before the end of this decade and long before the AGI/ASI threat hits us. But I don't believe we'll actually do anything about those threats on the horizon.