If you take the PCAT on October, your PCAT result will be received by PharmCAS around End of November to Early January. PharmCAS will then mail the test result on your designated schools 2 weeks after it receives the result. The disadvantage of taking the October PCAT is the delay on your application review by the AdCom. Although some schools may call you for interview first then review the PCAT score later, but not all pharmacy schools will do that.
I don't think the impact on your admission will be that bad, IMHO.