Nutrients or No Nutrients Hydro..... Please Help!!

How soon is too soon to start using nutrients for my babies. Info quick: Hydro flood system with 400watt HPS light. They are only 2 weeks old but looking very good. If I was going to use nutrients I was only going to use 1/4 strength. I have been told that I can use nutrients as early as 10 days, but then I have also heard that you should use nutrients after one month. What should I do? Any info would be helpful.
Thank You
Gotsmoked

have an ebb/flow table, i was able to go a few weeks before they needed any....different plants take nutes differently, good thing with hydro is, although its more tedious, fuck ups/corrections happen much quicker than with soil...my sativas could grow on almost pure water alone, all the way to harvest....just let em grow till you see signs of deficiency, then start from there...also, i went 1/4 strength my first go round w/nutes and burned the hell outta them, id start with 1/8th and work your way up...good luck!