I always go by what my ec wand says. I push my plants and imagine I'm heavy handed with the feed. 2 weeks into flower and I'm usually around 1.4 -1.6ec or 700-800 ppm. Maybe it makes a difference how long the plants have been vegged for though, as mine get 35 days of veg before flowering so they are nice and big. As long as my plants aren't burning up I shoot to hit 2.0 ec or 1000ppm by week 4 of flowering.