Most of the time, when I attach music to characters, it happens after their creation. Sometimes it's the last entry on my character profiles; sometimes it happens months or years later, often spontaneously as I stumble across just the right song.
However, sometimes a particular tune is so evocative that it suggests a character in my mind. I come up with a lot of my concepts through a collision of two unrelated ideas, so I have a character in my files who resulted from the dual inspiration of these two high octane songs:
13 Little Dolls - Sophie Ellis-Bextor
America's Sweetheart - Elle King
(This is one of those where this is the first I'm seeing the music video. Roller-skating, huh?)
The character who resulted is a blunt, impulsive frontier girl who inherited her family's set of old-world sorcerous dolls ... totally unaware of their powers and with no idea how to use them. Each was crafted by a different ancestor, reflecting a different time period and often area of the world ... so that gives me a lot of room to explore the worldbuilding without bonking people over the head of it.
Does she has a story (or even a name)? Not yet ...