He's referencing two completely different sets of girls

Group 1: "so many girls in here, where do I begin" this is referring to any girls all scattered throughout the club

Group 2: "where them girls at" this is after the girl he's "about to go in" on says she's here with her friends, and that got him thinking, so that's when he said the aforementioned line, referring to not all of the girls in the club, but the scouted out females acquaintances. He would like to be around this girl and her friends.