You are a parent -- not a student. IEP meetings are appointments -- just like any other business. While I try very hard to accommodate educators time, if I need to reschedule, I do.
When I have to reschedule, I do it in this fashion:
Regretfully, I am not available to attend the meeting on (date) at 2:15 pm and need to have the meeting rescheduled. The meeting will have to be after 3:30 pm. Presently, I have the following dates available:
5/22 @ 3:15 pm
5/25 @ 3:30 pm
5/26 @ 3:45 pm
Please let me know which would be most convenient for you.
Do not be surprised if they don't want to meet after school. I've had the sd tell me or parents I work with that the meeting can't take place after school. That is incorrect information -- it's a preference on the sd's part.
Email and/or fax it -- preferrably both.