start looking when your favorite region is down by 50% according the S&P res RE index, IMHO.
It won’t happen in the specific zip code I’ve been eying for nearly two years, since RE prices have stayed positive throughout(though down to single digit annual appreciation).
Funny, the RealtyTrac maps show nearby and newer developments with large clusters of red balloons, meaning lots of foreclosures (meaning 10, 20, and even 30 in a single new housing development). Obvious cases of developers doing some funny business with mortgage qualifications.