I applied to CMU before for Masters. Now, I applied again for PhD, ECE. CMU never changes. They have one of the worst admission processes that I have ever encountered.
As far as I can tell, they accept people and send their admission letters, then for the rest, some are accepted in Spring and they send them their admission. Finally, lots of people tend to be a fallback for both Fall and Spring. Now, in the two times that I applied, I got my rejection in May and June, respectively. Check the results page, you will see a plethora of rejects in May.
And yes, for me, third time applying to them and third time waiting beyond 1st or April; pretty sure it is a reject .