Long enough that they don't co-ordinate, essentially, which would show in how they acted. When facebook, twitter and reddit all announce the same kind of moderation changes within a few months of each other, you can tell that they're a de-facto cartel, and the specifics of how that happens (such as whether they directly communicated with each other) are kind of irrelevant.

I believe there are a LOT of people in the world that would think if your site does not come up in gooogle than it doesn't exist.

I remember reading that there are huge populations in which 'the internet' is facebook - so if fbk censors you - you do not exist.

Also, your site will not come up in google.

Google is just another social network that people are gaming (with the lazy consent of the people who run it.) Even if you make it, you can be wiped off google as easily as off twitter, no matter what your traffic.