You have at least another couple of weeks. See my pics of 67-day-old WW here, so both have been flowering for about the same time. That's definitely nute burn - you gave it too much at once. Flush as suggested, but at this point you may want to continue with straight water. On my next watering, I'll start using straight rain water . I usually start fertilizing after the first real fan leaves develop and I use about half the amount recommended at every watering.
What kind of lighting are you using - just curious!