If I'm honest with myself, I'd say that I knew on the first day. But, it wasn't my legacy chapter, so I was terribly torn. Recruitment was a month long for me, and the entire time, I was torn - so I preffed ADPi & KKG. I ranked them that way, too, and while I would have been happy in either, I'm SO glad to be an ADPi! FWIW, I wrote a retro recruitment thread a few years back - I always wished I had given DZ more of a chance, just in case!
ETA: It's
here. I thought you might want to see it, if you're considering Pitt. It's changed A LOT since I was there, though!