I think they start rolling out in June? At least that is what happened last year. They come out in shipments/batches, so anywhere from early June thru August.
Look Books (lists of items stores carry) are available several months before the actual release dates (bags start arriving in MJ boutiques around april-may). You can always call your local MJ boutique and ask to be notified when information can be given to the public.
Fall 07 stuffs are shown to certain 'people' already. Dued to various reasons, I don't plan on posting the entire look book for the upcoming collection this time.