When do you know?

Today I found a competition on thenest.com for a three day resort getaway! To win, people have to judge your "when you knew you were a couple" moment. The contest got me thinking about a similar question- how do you know when you've found the one?
For me, I think it's hard to narrow that feeling down to a moment. I could name several instances when I knew that Robert was the right one for me; the night we met and I came home singing his praises and not my blind date's; when he started including me in his future plans and discussing his life changing decisions with me (something none of my exs had EVER done); and what may seem like the most random and unlikely of moments was when we spent all day cuddling and watching Scrubs.

We were about a year into our relationship, and it's not like we were doing anything that belongs in a romantic movie, but I was happy just laying there with him mindlessly watching T.V. At that moment I felt like I've never felt with any man- like I was home. I realized I'd found someone I could actually picture my life with. Even if we were just sitting at home watching T.V., which let's face it, that's what most married couples end up doing. I had found someone who I could be happy with even in our most do-nothing moments.
But then again, I knew something was different with Robert from the beginning. As cliche as it sounds, I just knew. Things just felt different with us. The "Scrubs" moment is just when I was able to give words to the feeling that had been there all along. So can I really call this the moment when there were so many incredible moments before and after?
What do you think? Is there one moment where you know or do you just know all along?