My portal opened in early July, only because I had sent my transcript in and had my NASS CFA score to transfer. No one from USMA notified me that it was opened, I just checked one day.
That said, I just received the "Portal Open" letter yesterday in the mail. It had some pre-addressed envelopes in it for sending transcript, etc.
So, if you have competitive stats, yours might be there today or Monday.
ETA: I don't know exactly how it works, but each Regional Team might be one or two days ahead/behind another Regional Team in determining which candidates go to the next step.