How long does it take to get to each benchmark, 1000, 1200, 1500, 2000, 2200?

I think if you practice enough, you could likely reach 2000 rating on chess.com in about 2 years. I started my account on January 1st and I am almost 1000. You just have to practice tactics, review games, and play enough games too. You also just have to be willing to change your training plan as you reach higher elo. What worked for you to get to 500 elo will probably not work to get to 1500 elo. Most importantly, do not play like 20-something games in a day, because that is the easiest way to lose a bunch of rating or just lose interest in the game. Remember it is about enjoying chess, too.
You have no idea what you are talking about. I would be surprised if you reached 2000 chess.com in 24 months. Even if you do, it is not a linear progression and reaching it in 2 years does not mean in another 2 years you will reach 3000. Especially around the 2200 range you start facing serious players in the blitz pool on here—titled players etc. So without a lot of work you will likely just plateau before you even go beyond 2000.
I never said it was linear. What I said was that you need to change your methods of practice when you reach new rating levels. I literally said that reaching 2000 elo requires lots of practice. Maybe actually read what I wrote before just spewing nonsense and accusing me of things I didn't say. Depending on how much time you spend per day ( with some talent involved) and how you use that time, it could take you as short as 2 years to reach 2000, or it might take you 5 years.