Comes in waves. They are still reviewing applicants, and also getting responses back - I am on the Class of 2020 group and a few kids just today have left citing they were accepted to other schools higher on their list such as USAFA and USNA. As these rejections occur, I am sure that admissions recognizes more spots are then made for current applicants. I finished my application for RA back in November and found out about my appointment early March...so I totally understand your anxiety. Just know that the end is near! You will know by the end of this week or early next week, at the latest. Keep in contact with your AO and maintain a positive attitude
Best of luck!