Seedling Q

Recently i started two seedlings between paper towels with a dome over then transplanted them into rock wool cubes (i didn't have the cubes initially so the seeds couldn't start directly in the cubes). However i may have taken to long in getting the cubes and the leaves have already begun to show (very light green and just starting to appear). I am worried about exposing the plant to light too early. I have a 250mh light and can have it 4-5 feet about the seedlings if needed.

any help/advice?

I would keep it more like a foot and a half-2 feet max a for a week and then lower it to as close as possible. i have a good vent setup and normally keep my plants 4-6 inches from my 400w hps. if you can hold the back of your hand under the light at the level where the plants tops are for 30-60 seconds and it doesnt get uncomfortably warm your good.