Most Helpful Guy
Usually you know you're into a person the moment you ask her out (at least for me, since I'm not a club/bar guy or pressured by peers to approach remotely cute girls).
After the first date you know for sure. Once that happens, you either cease to engage or tell her straight up that you're not interested anymore. Most people stop communicating because it's easier to say "glad that's over with" and move on.
That's why first dates should be simple with no distractions so you can learn about the person. By the second date, you test that connection by introducing some form of challenge that requires cooperation. Make sure it fails, then see how she handles it. You can call it "the canoe date".0