If you have a cool tube or adequate venting you can go MH right away. It's like that saying, whatever doesn't kill ya... I mean think about all the plants that sprout and grow outside with no help. Had a 5 day windathon here a few months ago and I was worried it was going to tear the plant out of the ground, it was literally 40 degree bend in the wind and it just made the lady stronger i think.
It reminds me of a friend who grows cacti, he babied one with too much low light and then when he put it outside one day all of the green cactus skin turned black... we thought it died but eventually it turned around and was ok. We talked to some experts on the subject and the shortest explaination i can give is it got sunburn and did nearly die from shock. However it's fine and growing again.
Too much low light will train it to be a sissy all it's life.(my opinion not sure if it's really true, i only have this one experience to base it off of)