I just took the September ACT today, and I don’t think I did really well on it. I’m planning to take the October ACT. Do you think I can submit my October ACT score on time for early action?
no
you should not be asking here. Each college clearly states which test deadlines can be used for Early or Reg decision. THERE is your source. You need to get accustomed to using that prime source-- not this advice forum.
BTW: @theofrelord is simply wrong. Many schools accept the Oct sitting.
It depends on which school.