Wondering how long it takes for breathing to start feeling normal?

Hello Redditors and congrats to all of you that have quit or are on this sub because you want to try. I have a question for you quitters. How long did it take for your breathing to begin feeling right? I haven't smoked cigarettes in 19 days and I was a smoker for about 12 years. Also, I hacked up some brown stuff but not a lot. Will there be more of this?