I am an Australian national who will go to Austria on a student exchange program later this year. With the Australian passport, I will be able to travel in the Schengen Area visa-free for up to 90 days.
However, for the purposes of my exchange program, I am aware that I will need to obtain the Austrian National Visa D prior to my arrival in Austria, i.e. I need to sort it out in Australia, as I was told so by the Austrian Embassy. I also understand that with the Austrian National Visa D, I am allowed to travel to other Schengen countries under the Visa D.
My question is related to entering (and staying in) a Schengen country other than Austria before actually entering Austria, given the fact that I have obtained the Austrian National Visa D prior to my arrival. Say, on the day that my Austrian Visa D is valid, I fly into Italy instead of directly flying into Austria, and stay for 2 weeks in Italy, before eventually entering Austria via Italy.
Under the aforementioned circumstances, given the fact that my Austrian Visa D is valid at the time I enter Italy, will I be traveling using my Austrian Visa D or will I use up the 90 days visa-free quota that is applicable for Australian passport holders?