Hi, my Name is Niklas and I already worked as a tutor for german, french and english. I also started learning chinese and spanish when I was in school, so I can teach you my mother tounge in about 50 days.
But this is just a rough estimate, some people are a lot faster and I think if you are really as dedicated as you mentioned in the job-description I think we can even do it in 30 days, dependig on how fast you learn.
We will skype regularly (preferably about an hour per day), on weekends a bit longer. Of course I will provide you with enough learning material so you can train between our skype-sessions. If you invest 2-3h per day (skype-time included) you will probably be done in 30 days already.