Salt build up in coco/perlite

No need to flush at all, they are beautiful and healthy. So I consider u don't flush unless u have a issues, like calcium build up, nutrients lockout etc etc but if u decide to do flush wit h I don't advice then yes next watering u can feed.also your ppm is perfect for her age.Best of luck

runoff can be a bit higher than what is actually in the substrate. If you are religious about your drain-to-waste runoff, like growerofthemonth mentioned, all is well. (it will maintain equilibrium if done properly) if you haven't been consistent with it, it could be a cause of elevating nutrient levels in substrate. Plant doesn't dictate any pressing need to light your hair on fire. flushing is for imminent catastrophe... A little extra runoff after a slight formula change should be sufficient to shift contents of substrate immediately unless it is a crazy drastic shift in ppms for any 1 molecule of need.... then, it may take a couple irrigations before new equilibrium is reached. Can always water with a little extra runoff beyond normal, too... just avoid a volume that causes plant to droop (overwatering). tht will mainly depend on how well your substrate drains ( % perlite etc).

There is no reason to flush. Just have fifteen percent runoff. Best of luck the rest of the way.