it was in 2004, when I realized that maybe I shouldn’t be renting and should look to buy something, since some of my friends has purchased and were going on and on about how “rich” they were because of their new-found equity. I looked and realized that even with a decent salary, all houses around where I wanted to live were way out of my range unless I used exotic financing. I was not comfortable with that at all.
I ended up buying out of state and renting it out. Sold in ’06 and made some money on it. Before I sold, somewhere in ’05, I knew that there was probably a bubble. It was ’06 where I realized that it had to collapse though (thanks to this site and others).