“Rather later, she would attempt to pinpoint an exact moment when it happened, and she never had much luck with that—maybe it was months earlier, when he appeared on her front porch in his stupid hat, or on the platform on that wretched September 1st, or maybe it was long ago, in some unrecognizable, ever-changing form, but whenever she thought about the matter in the months and years to come, she knew with absolute certainty that it happened no later than this moment. Possibly Lily did not fall in love with James Potter that night, but, she would later conclude, there was no time after it that she did not love him.”
Book:The Life and Times