informal recruitment

Not all of the sororities do informal recruitment and it's difficult to get a bid as a junior even through formal recruitment but if you're thinking about it, might as well try

Informal recruitment is not organized by panhellenic. It is an individual thing done on a chapter by chapter basis, and a chapter can choose to do informal or not. How and when they do it is up to them, and they don't have to announce it or make it a public thing. Chapters often privately reach out to just a few girls they already know. There are very few bids offered in informal; they are not looking for a new member class, just to fill a few open spots, if they have any. If you are interested in a particular house, you need to contact them and ask them if they are doing informal and tell them that you are interested. Knowing girls in the chapter is your best chance.