I do not know if the comparison makes sense but in the 2003 Iraq War, Baghdad fell a month into the invasion and a after a week of battle in the city.
This may be a good point of reference to assess the curent progress of Russia's invasion, knowing that :
1. Ukraine's infantry is better than the Iraqis
2. Russia's technological superiority to Ukraine is relatively lower to US/UK superiority to Iraq
3. Iraq's army was outnumbering the invader by 4 to 1 (including reserve) which is more than 3 to 1 of Ukraine.
4. Weather for this war is winter/snow though it's only a week earlier.
5. Way less indirect ally support for Iraq than Ukraine has
There may be more divergences obviously but on the scale of operations and overall strategy, i see plenty of similarities and it seems to be the closest war we can compare to :
- Kurds being the local support like Belarus and Donbass/Lougansk separatists are
- Pincer strategy from 3 fronts
- Air superiority by the invader (Russia seems to be less efficient though)
With that in mind, I think it's probably too early to judge Russia's advance as the time frame to take Kiev should probably be a couple of weeks at least. We are having an orgy of information every hour since it's started but realistically most are meaningless in the grand scheme of things and we may not yet get the proper bigger picture. I think next week, we'll probably see clearer.