When the line starts going up again the bottom just passed.
I don’t think its possible to call a bottom except via hindsight. Which is kind of ironic given that everyone claims that about bubbles as well, which obviously isn’t true.
Gotta agree with kewp.
The problem is that the bottom of the market will look very similar to how the market looks now (weak sales, prices plunging, etc). The only difference between the bottom of the market and what the market looks like right now, is what happens after that.
The good news is that the housing market moves rather slowly. One can get in well after the bottom and still do quite well.
The bottom will happen when people stop worrying that this might be the bottom and they might miss the rebound.