I'm sort of in a similar boat, though my GPA is slightly lower than yours and my DAT is slightly higher. I'm retaking the DAT, but gave those 23 schools I applied to, advanced notice that I'll be retaking it during the first week of November. I sent my applications in already, because I didn't want to get caught late in the rolling admissions cycle at some of those schools.
But I did have one question for you -
I don't know how rigorous your grad biotech program will be ... but being knee deep in grad work and prepping for another round of the DAT might leave you a bit stressed for time. Do you think you can swing for the fences on both ?