well, most schools will send you a secondary regardless of your MCAT. But it seemed to me that most said that they wouldn't consider an application until it was determined "complete," meaning that all secondary materials, letters, etc. were in, including your final MCAT scores.
so, if you are asking if you will be considered late, not really, but yes, in comparison to people who aren't waiting for august scores. a 30 is high enough to get interviews, but I don't think anyone will look at it if you check that box telling them to wait for August scores.