Suggested letter (others probably will have commentary on this, but it will get you started):

Quote
Dear Dr. Late,

I received your message about your new expected date for a report. I understand that these things take time to complete, and I wouldn't want you to do less than your best work. But the last day of school is May 28, and I am concerned that if I don't have a report until May 14, the school will be unable to implement any of your recommendations in time for fall. Would it be possible to get test scores, without the full report, now? That way I could get a meeting on the calendar before school gets out. I won't share the information with the school if you don't want me to - I just want to know whether to proceed with requesting acceleration or not.

Thanks so much for your help with this!