I think it would depend on the department. The only recruiting invitation I received was after admissions decisions had been made (was a Fall 2010 NYU applicant) and the event was a way of trying to entice newly admitted students. There are several forms of orientation/recruiting events, each one varied from school to school. Prior to admissions decisions, some schools/departments may host an open house event - in which any prospective applicant can attend. Usually, it's a great way to meet the department, current students and faculty, as well as see the school you'll potentially be going to. It's also a great way to score some free food