Since they're already shelling Kyiv, they obviously have more options than tanks to take ownership of the governmental apparatus.

I can't see how Ukraine can put up any realistic defence given they now have no radar tracking or air support.

If your point is "it takes tanks a few days to get to Kyiv", then, yes, that is technically correct. If your point is "Russia needs to invade the whole country", no. They own the country when they control the governmental apparatus in Kyiv.

The US did not control either Iraq nor Afghanistan when they took Baghdad or Kabul, respectively. That‘s not how a much weaker force fights nowadays against the more powerful opponent.

I believe russia has already fully integrated the idea that this will shift to a guerilla war once they have complete ownership of all the country. Nor is Ukraine (or Russia's way of maintaining control over a country once they occupy it) is really analogous to either of those countries.

I think you underestimate how easy it will be to take control of the government and country.

Ukraine knew that they would be able to take Kyiv quickly. Intelligence sources have been saying that for weeks. They (Ukraine and it's friends) have been preparing for this - openly talking about partisan style resistance.

I'm willing to bet that they need to seize pretty close to the entire country to maintain any sort of control.

I suspect Russia will just keep slicing the sausage. Then take the western provinces and re install a puppet regime as was there before (like Belarus). If that turns out to be inadequate down the road, just take another slice or two down the road.

The USSR went partially this way in Finland: sliced off half the country, though they left the other half alone, on sufferance. I don’t think Putin would be satisfied with that: he’ll want another Yanukovych or Lukashenko.

Update: I was totally wrong!

"By sunset, Russian special forces and airborne troops had seized the Chernobyl site and were pushing into the outskirts of Kyiv." (that's an update from NY Times. We can imagine that special forces will proceed to the government house and presidential office building through tonight and have ownership by tomorrow)

Troops entered kyiv, some 19 hours after you made your statement.

Should be ~35 hours after my claim now, the "overnight, next day, and next night" mentioned has now passed.

It appears that heavy tanks have yet to even reach kyiv. Lighter vehicles and paratroopers have, but failed to seize the city overnight. The vast majority of Ukraine remains unoccupied, the takeover attempt is far from over like you claimed it would be.

I was wrong.

My statement was not about how long it will take them to take Kyiv, but rather Ukraine. I had actually thought they would reach Kyiv before now.

I still believe my claim. Unless Russia miraculously takes the rest of the country in a few hours it will come true.