Submitting December ACT scores to UT Austin?

I'm applying to UT Austin next year, and I'm curious whether they will accept December ACT scores for a regular decision application. Will I be able to submit scores from the December 10th test date? Or do I need to plan on taking my last test in October?

You won't be able to submit scores from the December test date; UT Austin requires that all application materials be received by December 1st. Aim to take your final ACT in October (at the latest!).

Source: http://catalog.utexas.edu/general-information/admission/undergraduate-admission/