Instead of placing a fixed timeframe on buying (wait a year or until winter), why not track the market and wait until prices stabilize or start to track up.

Apply a longer term moving average (MA) to home prices and jump in with that levels out. Using an MA will reduce buying spikes that may be transistory while giving you a better picture of the long term trend of prices. You will not catch the exact bottom, but you will not have to worry (as much) about catching a falling knife. Of course this method is not foolproof, and prices could level out for a substantial amount of time, and then track down again, but combined with the fundamental price ratios its better then guessing.