It takes us the months of October and April to study and select six months worth of lessons.
Many of us have been in your shoes, and understand the prayerful care you are taking to be inspired with the Conference talks you select. That said, as stated above by russellhltn, GHB 8.2.1.2 is pretty clear. Given that the first EQ/RS lesson is only a week after General Conference, I'd suggest you would be able to at least quickly choose the talk for that lesson (choosing the Prophet's message would always be a good choice!). And while that doesn't give the teacher that much time to prepare, it seems the Church is instructing us to begin using the newer messages immediately (even if it does present a bit of logistical considerations). Then you can use the needed additional time during the month to select the remaining lesson topics.