Another thing to keep in mind is that these are not achievement tests. Although a child may well do "better" or "worse" on any given day the theory is that IQ should not change that much. Whatever your DD scores on the WISC now, theoretically she should score pretty similar in 2 years time, because it is not supposed to be testing what she has learned but how she thinks. So the school should not need WISC results done at exactly 7 1/2.