Fall Informal Recruitment here at KU is very different for different organizations. Some Fraternities participate in fall informal recruitment in order to obtain fall new members. Some participate only to recruit for a spring new member class. And some just get an early start and will recruit in the fall for the following fall semester. It depends on the organization, and it will change from year to year based on how well recruitment has gone for them. In general its best to just ask whatever organization you're interested in to see what type of recruitment they are participating in.
In addition, during the fall semester we host an IFC Experience Night hosted at the KU Edwards Campus in Overland Park to jump start Fall and Spring Informal Recruitment. So keep an eye out for that when Fall rolls around, and otherwise contact chapters you are interested in to learn more!