I think that "arrival" of AGI will probably be a few AGI made by competing groups all around the same time. They'll probably run on supercomputers. I don't think these systems will be among the top 10 most powerful at the time, though, because these are usually running multiple government projects as opposed to having all resources devoted to one project.

After that initial time period, I'm sure they'll be as many AGIs as computing resources allow. Therefore, more and more will exist over time.