Somewhere there's a post with the historical release dates for Southwest flights, but that only can serve as a general guide for when fares might be released. In general, SWA puts out its fares and schedules 4-5 months in advance. I know, for example, that dates through late October have been released in the first part of May in the last couple of years. That would leave November fares available in the June/July time frame. If I had to guess, I would say July since SWA rarely releases dates in consecutive months.