Hi,

Well it depends on the university or college you are applying to. If you give your exam in December then you will have to go for regular decision in all the universities because the early decision and early application closes by October or November. The college needs your score before the deadline to review your application completely. Still you can email and ask the admission department of respective universities about the same and they will be more than happy to help.

I hope this answer helps.

All the best.