As other people have mentioned, assuming you are in the US, there is no such thing as accommodations before the date you are informed of the disability. Students are required to provide the information from the office on the campus to the professor, and it is up to them to make the choice about when and to take the consequences.
However, I'm also concerned about something else you said. Accommodations never should reduce the expectations for students. They cannot excuse a student from doing the work. What they are supposed to do is to is make it possible for students to do the work. Most common is extended time on tests. Sometimes they have a note taker. Or they need to have adaptive software, like a screen reader for blind students, or an ASL interpreter for a deaf student.
Not doing work for months in every class every semester, then requesting "accommodations" at the end of the semester that amount to significantly less work than the average student.
If you have a group of faculty who think that a student has done this repeatedly, then I think that you should speak with whoever runs that department (in a respectful way) in a face-to-face meeting, maybe with your chair. Also, you might want to document the whole thing if it is really the same student over multiple semesters or in multiple classes. This will let you get clarification about these issues. But it also lets that person know that they need to meet with the student in question. (Even if it is multiple students, I would handle each one differently.)
I was going to suggest next steps, but it really depends on what happens.
If you don't already include an "Accommodations" section in your syllabus, you should add one that explains the procedures and spells out your expectations about notification.