Harry's realization that he likes Ginny Weasley occurs in Chapter 14 of Harry Potter and the Half-Blood Prince.
While the reader might notice signs of Harry's developing feelings for Ginny earlier in the book, Harry himself is slow to understand his own emotions. According to the provided reference, textual clues suggesting Harry's interest appear before he is consciously aware of it. The first textual sign mentioned in the reference is in chapter 7 on September 1st, during the journey on the Hogwarts Express.
However, Harry's personal realization of his romantic feelings for Ginny happens approximately two months later. This significant moment occurs in chapter 14, titled "Felix Felicis," when Harry witnesses Ginny kissing Dean Thomas. Seeing Ginny with someone else triggers a strong emotional reaction in Harry, forcing him to confront the depth of his feelings for her.
This specific point in Chapter 14 marks the moment where Harry consciously acknowledges his romantic attraction to Ginny, shifting from subtle, perhaps unconscious, interest to a clear understanding of his desires.
