"If you’re a high school student, you should apply early in your senior year; admission will be much more competitive if you apply later. The freshman application is available beginning August 1 .
“* Priority application deadline for computer science, nursing, professional flight technology (Priority means we will continue accepting applications after this date only if space allows — if applying for one of these programs after November 1, check the closed programs page first.)”
Note that CS is already showing as “closed” for Fall '21: Closed Programs - Undergraduate Admissions - Purdue University