Everyone's different, it's impossible to say.
I do think though even if you start at 20 it's not too late to be expert or even master. I think the amount of work required surprises most people though.
Anyway it's a good goal, go for it. Set small goals between too e.g. +100 to your current rating.
Hi all. I had a quick question on what you thought about the potential max ceiling of myself. If I put the time and the effort in my goal is to be rated 2000 in lets say five years. I learned chess when I was eight and played roughly 800 games up to now (standard time) in which I am now 20. Now for the past three weeks I have been hitting the books hard and studying. Am I too old to be rated 2000 in my lifetime and be an expert or perhaps master.