ADHD and 504

How does one decide whether to do a 504? And when does it usually happen?Our daughter, age 5 but not yet in kindergarten, was evaluated by a neuropsych. She found several deficits, but - like previous IEP meetings we have had - said our daughter scored too high to qualify for special education. Because of her ADHD diagnosis, she suggested a 504.I am unclear as to when to do this. Should I try to get one in place before she starts kindergarten next year, or should I wait and see how she does? (By the way, I am scared to death about kindergarten...she has very poor fine motor, poor self-regulation, SI...the list goes on).