FIrst time grower and very confused..

Hi everyone! im a first time grower and in need of some help! I got a 20 gallon airoponic setup with 8 nooby plants in them that i started from seed.. i germinated using the paper towel method and transplanted them into starter plugs.. (dont ask me why i didnt just start them in the plugs.. im a retard). Should i have just transplanted them straight into the hydroton rocks? if so is it too late to just pull em out of the plugs and transplant them in? Also when is a good time to start adding nutes? also with the starter plugs and wat not do i keep the water pump goin 24/7? or should i use a timer and water 1 min per hour? well hope u guys can help me start in the right direction. THANKS!!!

ill post some pics up soon, my camera is broken right now.. T_T. but yea the plants are about a week old from seeds and they average about 4 inches with no leaves yet.. just the sprout. it is also a bit yellowish green, which i believe is due to overwatering... so i turned my pump off for now to see if thatll do anything. also it might hav been due to a lack of light.. i do have a 400 watt hps and a conversion bulb so im thinking of starting to use that in about 3 days?.. when they are about 6 inches in height with some leaves?