There are no problem to take a house after three months of your apply for asylum (it's depends on availability of house). I took one small apartment recently. It's cost around 400 euro with everything (NK), and Rathaus paying (I have to pay electricity bill) the amount though I haven't finished my asylum procedures yet. I gave interview five months back to the Bundesamt.
So in a small: if you find a resident then take a special form from Rathaus and filled up by your house owner, after that give it back to Rathaus, they will see and then you can get permission to take this house.