Company/country X has an AI agent that can do 99% [edit: let’s say “automate 90%”] of AI R&D tasks, call it Agent-GPT-7, and enough of a compute stock to have that train a significantly better Agent-GPT-8 in 4 months at full speed ahead, which can then train a basically superintelligent Agent-GPT-9 in another 4 months at full speed ahead. (Company/country X doesn’t know the exact numbers, but their 80% CI is something like 2-8 months for each step; company/country Y has less info, so their 80% CI is more like 1-16 months for each step.)
Spicy take: it might be more realistic to substract 1 or even 2 from the numbers for the GPT generations, and also to consider that the intelligence explosion might be quite widely-distributed: https://www.lesswrong.com/posts/wr2SxQuRvcXeDBbNZ/bogdan-ionut-cirstea-s-shortform?commentId=6EFv8PAvELkFopLHy