How long does it take to get good at Violin? (finish beginning)?

There is no accurate way to answer that question because there are two problems with it. The first problem is that everyone defines "beginner" differently, so from one person to the next you are going to get a very wide difference of opinions even if all of them agree on approximately how long it would take to learn a certain set of skills. The second reason is that everyone progresses at a different rate, and you will be better at some things than others and therefore won't be consistently above or below average. You can't even accurately predict your aptitude before you start learning to play the violin, so it doesn't serve any purpose to make guesses. If you set a time-sensitive goal and for whatever reason don't reach it, you could get discouraged and quit altogether. Worrying about how long it takes you to get to a certain point is setting yourself up for failure. It's better to just enjoy the process of learning because you will never be finished learning, anyway. There is more violin music out there than you could learn over several lifetimes.

Good at violin? About half a lifetime of constant practice.

Define 'good.' Master violin players take 20 years to be good.

Beginner level generally takes somewhere between two and five years, depending on the quality of your instruction and how hard you work. If you're trying to teach yourself, count on more like ten years.

i just said finish beginning, i not mean play like master