I still would argue that at a younger age they will not need as much food. I mainly grow in soil and have had seedling and clones that I put into hot FFOF and had them burn a little and assume it is due to the nutes in the soil....and from there I would not feed for 3-4 weeks or until the plant tells me to. I am newer to the hydro game and DWC.....but all that I have learned and read would tell me if I started out at 800 to 1000 ppm it would be to much and I have never tried it to be honest. I always start off slow (1/4 strength) and work my way up. It just makes sense like a baby child would not need the same nutrients and eat as much as a grown man. If you force fed him what I eat and make him take down a 16 oz steak, potato, etc he would surely get sick. As he grows into his teen years that protein would make he grow bigger and stronger. My first hydro run on a ebb and flow I thought more was better and tried ramping up quick on the nutes....guess what all it did was lead to over feeding and lock out. There is a big difference between organic food and salts (chemical ferts) so your soil argument doesn't apply here...There are always going to be different opinions but I am not one to try and force 5lbs of shit in a 1lb bag....meaning I don't overfeed let the plant dictate what it wants, keep it green, not into all the super blooms (snake oil), I don't keep my lights 4" from my plants, etc....and I don't really advocate flushing either (soil). Of course if you have overfed with salts the whole time or hydro it is a good idea. Not saying it is bad to push the limits but you need to know the plants genetics and have experience before you do so....So for noobs and most people yeah lets cover our asses
If he wants to become a mad scientist with his plants then he can check out the advanced growing section and build what he has learned from this go around.
Personally I would start off low (200 ppm) build up (peaking mid flower) and then come back down as the plant finishes....I would also use a CFL or T5 to start my seedling and have the light a little closer as it starts, then as it gets bigger put them under 400. So church what PPM do you start a young plant from seed and how many PPM's do you give your plants? Are you a steady 500-600 PPM?