Too early, there are no signs of preflowers yet, which depend on age, not the number of nodes.
Plants will show primordia (pre-flowers) long before flowering in earnest begins and does not require going to 12/12 to initiate primordia, only for decisive flower growth is 12/12 needed. If you intend topping, do so as soon as your plants have reached the size at which you want to top them, do not wait for primordia, topping long before going to 12/12 is best for your plants.
For pictures of male and female primordia, and other cannabis behaviour, go to my diary "cannabis conundrums" and in week 7, you will find them.
Hope this helps,........
Organoman.