When Should I apply to Purdue CS Program?

I know that Purdue starts accepting applications beginning August 1st. However I would like to get my ACT score up before I apply there. I’m sure I can raise my ACT score a few points at the Sept. 10th test date, and the scores would be sent to Purdue at the end of September. Currently I have a ACT of 27 (but would like to get it up to a 29/30) in order to increase my chances of getting in. I have a pretty good GPA of a 4.5 weighted and a 3.9 unweighted. I am ranked in 10 in my class on 520 and I am involved in various things including:
-National Honor Society
-National Technical Honor Society
-Vice President of National Spanish Honor Society
-Member of Key Club
-Member of BioBuilders Club

I have taken or will take these AP Classes:
AP Computer Science
AP Physics I
AP Calculus
AP Literature/Composition

So my question is if I should apply at the beginning of August and send my current ACT score, or if I should apply at the end of September with a higher ACT score?