SF, feel free to disagree with me any time you like!
You are correct that an IQ score below 115 is considered a rule-out for acceleration, so it is possible that a school may push back without the IQ score. But since the OP's school has already offered an IQ test in the fall, without the achievement data, it seems worth the try to go for a (perhaps provisional) skip agreement during the summer, where the family appears to value starting the year in the child's long-term placement, and the achievement scores may be strong enough to support a skip, rather than waiting for a skip during September.
Another option is to check existing school records for any other measure of ability, such as the CogAT. The OLSAT and other group standardized ability measures often paired with school-wide achievement tests are not considered primary measures by the IAS, but it might be a selling point to the school, if a score of this type is in what would be comparable to the qualifying range.
