There is a saying that you have to learn to think in the language which you would like to learn. Once you think in the target language then you know you are pretty good. People say it as if you get to a certain level and then it just suddenly happens in an instant – you start thinking in the new language.
A Gradual Process
However I once heard a language expert talking about this and I must say I agree more with what he said, which was that learning to think in a language is a progressive process which starts from day one. For example, I can say “si”, “no” and other simple words in Spanish without thinking “yes” and then “translating” this concept into Spanish in my head. However if I wanted to say “I just finished writing a blog post” then I would have to consciously translate the phrase. Over time you become familiar with phrases and they gradually become things you can say without thinking. So, over time, you do indeed learn to think in a new language but I reckon it is definitely a gradual process.
Learn Spanish (from Spain) 
Learning to Think in a New Language definately signifies that you are progressing along nicely. What an interesting relevant post that all second language takers should read.