If we get to 'great pharmaceutical models', then curing common diseases is likely to happen as test cases on the side before aging is finished (even if a company throws billions immediately at aging, even with great pharma models it will still take time). Or you just have pharma companies not focusing on curing aging that hard, and just throwing a bunch of effort at various diseases.

If we get to AGI, and it is aligned, then Aging might be solved earlier due to it being a significant problem. However it has the benefit of scaling better than human organizations (hard to copy a human researcher) so it spins up enough to cure a bunch of the common diseases while it also does aging, making cryo definitely work, etcetera.

How do we tell if aging is cured?

The common cold is just a viral infection like any other. Aging is so much more complicated.