This older article of mine should answer most of your questions: https://medium.com/writers-blokke/just-reached-2k-followers-and-you-wont-guess-how-long-it-took-a24f8becc045

I would also highlight the fact that high follower-count more often than not doesn't proportionally translate to higher income. Just 3.5K followers in my case lands me in the yearly 5-digit club in terms of income (with no affiliate marketing), while many others with 10-12K followers still struggle in the mid 4-digit club by the end of the year. I much prefer 3.5K loyal followers than 12K that doesn't actually read. I always shoot for organic following and I never "sell" anything, and it worked out well for me.