I was the 504 teacher in my school.....almost 10 years ago. At the time, we had 30 days to respond to the parent, if not get the 504 in place.
A 504 plan is very easy to implement because it is NOT an IEP. It is just "common sense" on a paper to make sure the student's rights are respected and upheld.
Does your child have a diagnosis that is keeping her from learning? This applies for kids who have ADD/ADHD, a broken leg, anxiety, bad eye sight, etc. If you suspect a learning disability that is NOT previously diagnosed, you have to start at square 1. That's the process you are probably familiar with. Lots of formal and informal evaluations, observations in the classroom, meetings to discuss evaluations, and assessments from a school psychologist....then an IEP is written if the child has been diagnosed with an LD.
Students that are on an IEP typically do not have a 504 plan because it is redundant.
To assist your school with writing a 504 plan, walk yourself through your child's day. What obstacles does he/she have? How would YOU solve that problem? Your solution has to be easy for the teacher to implement *sitting at the front of the room, near the board, near the teacher, etc.
*getting extra time to get items from a locker or to get to class (student with a broken leg).
*allowing student to take backpack into classroom (some schools do not allow this) for students who need help with organization
*allowing student to use the bathroom or quiet corner whenever he/she has to (students with medical condition or anxiety)
*asking the teacher to sign off the daily planner for students who need help remembering or organization
*asking another student to help struggling student pack their bag for the day
*giving student extra time to clean his/her desk or more frequently during appropriate times
You are more likely to get what your child needs if YOU know all the issues and have ideas for the solutions.
Like I said, this is just common sense on a paper. In elementary you typically don't have teachers being mean or unreasonable with a student's actual needs (sometimes you do). In middle and high school, you get teachers who don't believe the kid or think that the diagnosis is a joke. They penalize kids for taking their backpack in the room, etc.
Good luck!!!