The process and timeline are really dependent on the school district. HK outlined the ins and outs of what's required, but fwiw, for a 504 plan - that can all easily take place in one meeting in our school district if you have a diagnosis report for a qualifying disability from a professional provider (private) or if you have been through an IEP eligibility process and found not eligible for instruction under an IEP but are eligible for disability accommodations.
If you don't have a diagnosis or outside testing, in our district you would have to request the testing in writing and then wait for a team meeting, the team decides if there is reason to suspect a disability and move forward with testing - if the team decides to test they have a specific number of school days within which to complete the testing (there is a federal law limitation and some districts have shorter time frames as policy).
Have you tried looking on your school district's website or just asking at the school? Most schools (here) have a designated 504 coordinator who can answer these types of questions.
polarbear
