“The Dean” is flying without radar here. It’s hard to answer your question without knowing where you’re applying and exactly how much below the median at these places your “on the low side” ACT scores actually are.
If you were a junior, I’d say that you should definitely wait to retake the ACT before applying. But your “Ask the Dean” form indicates that you are a senior, and so the clock is ticking. If your top-choice colleges have Rolling Admission and if they accept fewer than about 70 percent of their applicants, then you don’t want to lose out because you applied too late. Instead, send your application NOW but also email your regional admissions rep. (This is the staff member who oversees applications from your high school. You can get his or her name and contact info from the school’s Web site or by telephoning the admission office.) Explain to the rep that you are retaking the ACT and are hoping that your file will be reviewed after the new scores arrive.
If your top-choice colleges have a late admission deadline (in March or thereafter), you can wait for your new scores. However, some universities give financial aid and/or housing priority to those who apply early. So check the policies at each of your colleges before making a decision about when to apply. I also suggest that you take at least one ACT practice test to try to determine if your scores are truly likely to go up significantly. Keep in mind that practice test scores are usually better than the “real” ones, so if you don’t see a big jump when you compute the practice results, then get those applications out right away!
Good luck to you whatever you decide.