We always had my daughters IEP meetings at the end of the school year. Partly it was just timing but it worked out well because a teacher who has been working with a child all year has a better idea of what they need the next year than one who's still trying to get a handle on them. I think it's very reasonable for the old teacher's to be the one to come up with the accommodations.
And my understanding was we could change our 504 (DS has a 504) at any time if new or changed accommodations were needed. But getting any change while school is out for the summer would be difficult. What happens in my school district is the schools basically shut down about a week after school is out for about 6 weeks. (They don't get paid during most of the summer) And then staff & counselors become active again 3-4 weeks before the school year begins. So you might need to wait till August till you get any response. Check with the district or school for their schedule.
