This may be the busiest time of year for the psych, in terms of school assessments. Each case report may require careful wording to ensure the appropriate details and recommendations are thoroughly communicated. In creating a preliminary report or brief early summary draft, there may be room for errors or inaccuracies in understanding and interpretation.
IF you were to contact your psych to ask for a preliminary report, you may wish to begin with acknowledging that this is a busy season for their practice. If you receive a preliminary report, you may wish to refrain from asking any clarifying questions or details.
In general, the fewer requests for additional reports which the psych receives, the greater amount of continuous time which can be devoted to each report, and the more swiftly each report can be accomplished.
While the delay of two weeks may be quite inconvenient, the psych may have experienced an unexpected personal setback, such as illness, accident, or death of a loved one... something which may have taken extraordinary effort in order to minimize impacts down to two weeks.
I like the idea shared by another poster: letting appropriate school personnel know that there is something in the pipeline. You may also wish to inquire as to what opportunity there may be to review the report with administrators over the summer, in order to have some plans in place as to how things will proceed when a full decision-making team is assembled.
