Please excuse my typing in english, since I can not type chinese here.
I have a question concerning about "长期居留"

I have a french residence card, thus I have the right to stay in Austria for 3 months. I found a job in Vienna, with the first 6 months of trial period. I will have the contract if I passed the 6 months trial. The question is:
Can I apply the 居留 after I come to Austria? If I can't, I have to apply it before I come. what kind of "住宿证明" I need to apply for a residence carte for more than 6 months stay? I need a renting contract? or just a letter from the owner, showing that I will live there? cause I'm in france now, it is not easy to find a real contract. I can only find a temporary flat, then I will change into a stable one after I arrive.

Thank you very much in advance:)
looking forward to hearing from you