It takes as long as it takes. The question is how entertaining are you? Are you entertaining enough to keep 1000 people engaged for 4000 hours?
It's up to your viewers to decide how long that will take, and that's up to how entertaining you are. If you're only in it for the monetisation, people will see through that and won't bother. If you're just interested in providing entertaining content that people can't not watch, it will happen quickly.
Some people it takes years, some people it takes weeks. Focus on good content, not the numbers