Out of all the Academies, USNA seems to play their cards closest to the vest. Our son applied to USNA last year, and to both USNA and USMA this year... we were shocked at how much more info is available on the USMA portal!
I can't speak with any certainty about changes to the USNA portal after an appointment, but our son received the TWE on April 10th last year and his portal NEVER did change. He kept checking it even after the TWE because he was anxious to re-start the application process - one day several weeks later it was just gone, but it never looked any different than the day he finished his application. YMMV - Best of luck!