It's not helpful to think in terms of how long will it take. Everything about it can be so varied and arbitrary. What you need to do is trust the process and be happy when you have one of those moments where you notice there has been a significant positive change in your ability. These may happen after a few days, a month or two or even a year of diligent practice.

As far as doing it right, the best way is to go the official critique route. You probably can tell if some things are right by yourself but nothing beats feedback from an expert.