I agree with you on the basics. There will be permutations in the time line because of population decline, violence, political instability, and so on.

Plus one cannot rule out that desperation within the ruling elite will lead to some radical acts such as trying to seed the atmosphere with sulfur to mimic the cooling of a volcano. And nuclear war is a finite possibility.

Once chaos is unleashed tracking timelines will lose meaning in the short term. Longterm recovery to a new normal will take thousands of years.