Wouldn't you know: Another damn question....

So I shouldn't transfer the plants to the hydro set-up until the 2nd or 3rd set of true leaves... Does this mean that I should keep them in rockwool cubes under flourescent? once the roots outgrow the cube, i transfer to rockwool blocks?. The roots can't be exposed to light I know that much...

But i mean, for the first couple of weeks all I really need is a plastic cup and rockwool blocks / cube... Just pure water when the rockwool drys out?