I would go back to feeding them, myself... seed banks will always give you the FASTEST estimate of when the plants will be ready for harvest (they want to sell more seeds!) and they often bear little resemblance to reality!
I personally think you have several more weeks to go and would tell you to start flushing when you start noticing the fade - or when the pistils become mostly brown. You can pick up a jeweler's loupe to take a close look at the trichomes at that point - but if you start your flush when you start to see the fade, they'll be ready when your flush is done...
Good luck and happy smokes!