your canopy is not very bushy and your week 5 in flower, so you have to be careful, not saying
@jondamon is wrong about the plants needing nitrogen, but its likely to be at a low amount (6-5-6) may be too high, I would keep feeding the plants around 800ppm every water for another week and start the bloom as you said, don't stop giving the plants nitrogen, instead, you want to reduce it over over the next few weeks, you should be able to give the plants both at the same time, just keep the EC under 1000 and the PH between 6.5 and 7