when ever u have your first couple sets of true leaves.. You can actually veg under flouresents the entire time if u have some high quality ones.. but i wouldnt move em in there until they are about a foot, they could be put in before that im sure someone will say, just saying to be safe. u wanna make sure u have a developed root system to handle any stress and take in enough water and nutrients for the growth of a 400watt hid.. make sure you use MH for veg and HPS for flowering..
also i would recommend getting a T5 flouresent off of ebay for about $30-40.. or you can get a $30 T5 from lowes, although they are not quite as good as a T5 grow light from what i have noticed, but it would be a LOT better then a normal lightbulb..
this is also why u have stretching the plants are looking for the sun and that little light is like a flash light lol
mine went into my 400 watt tent just a tad smaller then this..
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