If you have to think, it isn't flow. Flow leads itself to where the moment is. Thinking is programming yourself and referring to some mental "lick library" you have. Copy band players do that because it is their vision quest to sound EXACTLY like the record. Like a little robotic jukebox. When you are truly into flow, just close your eyes and watch the little black dots go by in your mind as your soul takes the music where it wants to go.

ANY flow starts with learning how to play an instrument. Maybe try that.