About 3-4 years of serious chess for where I am right now, and 2-3 years to get my current (old) official rating, if you add up the time periods where I've trained seriously. However, I've known the rules since I was a little kid, about 8 years ago.
611 is very slow for 4 months of serious chess, but I'm assuming you haven't done serious chess training. You probably just play for fun / are only looking to improve casually.
when i created my account i clicked on new for my rating (i technically wasn't new but i was having fair games so it was right thing to click on) and after 4 months and 8 days on this site my rating has increased by 611 (800 + 611 = 1411) a significant amount of you would've had a lot of expertise before you created your accounts but if you can remember how long it took for you to get to where you are it would be great.
is 611 increase in elo rating in 4 months fast or is it average or even slow?