We woke up early to get some Cronut action (October's flavor: apple creme fraiche). It wasn't that bad; we got there at about 7:40 am and had Cronuts an hour later. Some people start much earlier than that.
Overall, I don't think it's worth waiting in line for a Cronut, but you don't know until you try it. Many of Dominique's other pastries are better (freshly made madeleines! DKAs!), and require no crazy waiting.