ACT submission?

Answered

No.

Detailed answer:

If you are using the Common App then you must inform the colleges you are applying to in advance whether or not you are going to submit either an SAT/ACT/both scores or no scores. In addition, you have to know how your individual test scores that comprise a super-score are made up of including 1.) Component Score, 2.) Test Date.

There is no option box called "possibly will submit an ACT score but let me think about it until after the test scores have been released after the common application deadline".

While this is a valid question I apologize in advance for pointing out that there is no practical solution to accommodating this kind of courtesy to HS applicants.

If this were the case, then everyone would be selecting that option and colleges would have to re-adjust all their sorting processes to include new categories called "likely to be waitlisted but waiting on an ACT score", "likely to be waitlisted but waiting on a possible SAT score", "likely to be deferred but waiting on an ACT score", "likely to be deferred but waiting on an SAT score", "likely to be rejected but waiting on an ACT score", and "likely to be rejected but waiting on an SAT score. I'm assuming all likely-to-be-admitted piles wouldn't change by an additional test score.