imo, and from experience, 12/12 from seed is not a great idea. the plant does not start to bud when it first sprouts, it isnt old enough or ready. it would be like a baby being born and saying "lets fuck so i can reproduce". it will start to flower at about the 3rd -5th node, so bout two(+/-) weeks. meaning that if you count the days flowering from the first sprout, you will harvest about two weeks early. well rooted clones, on the other hand, are cuttings off of a matured plant, so as soon as they have rooted well, you can throw em under 12 and start countin. i had two girls started 12/12 from seed on my last grow, and it was highly disappointing, only about 1/2-3/4 from each.