What is the current turnaround time for Vandenberg SLC-4E?

The answer to this question is the same as pretty much every question about private internal company secrets of SpaceX: we don't know. SpaceX is a private company, not even a publicly-traded private company. They are under no obligation to share this information with the public, and there is no reason for them to do so. In fact, there is good reason for them not to.

This is very likely a private and confidential trade secret.

What we can do, however, is look at the list of Falcon 9 launches from SLC-4E on Vandenberg Space Force Base and then we can see that the fastest turnaround was 22 days 20 hours 45 minutes between the launches of Starlink Block v1.5 Group 4-4 on 2021-12-18T12:41Z and Starlink Block v1.5 Group 4-11 on 2022-02-25T17:12Z.

However, all that is telling us is how fast SpaceX has turned around the pad in the past. It says nothing about how fast they could turn it around if they needed to. The thing is that there just aren't that many launches from SLC-4E that would force SpaceX to turn the pad around faster than they currently do.

There is an important difference between Vandenberg and the Space Coast, though: the Strongback at Vandenberg only retracts to about 20°. The Strongbacks at LC-39A and SLC-40 retract to about 45°. This means that the Strongback in Vandenberg sustains more damage than the ones in Florida. The best guess for why SpaceX did not retrofit the Strongback in Vandenberg the same way as they did the ones in Florida is that they simply don't need to: there are not enough launches from Vandenberg that SpaceX would need to turn around the pad any faster.

So, we don't know how fast SpaceX can turn around any of their pads, but we can guess that they probably can turn around the ones in Florida faster than the one at Vandenberg.

[Source: List of Falcon 9 and Falcon Heavy launches on Wikipedia and Vandenberg Space Launch Complex 4 on Wikipedia]