you can but some strains wont yield you more then 2-3 grams a plant!!! others will give you a 1/4 to a 1/2 oz. its better for you to just veg them atleast 3-4 weeks or ideally untill your plant has alternating internodes which means the plant is sexualy mature. this will happen in 4-8 weeks depending on strain, light, ect. if your going 12/12 from seed get a hybrid 50/50 mix or purer sativa since pure indicas need to veg a while to give you any real weight. and no it wont be pretty much an auto strain since plants will veg 2-4 weeks anyway under 12/12 from seed depending on strain. your better off picking your best most potent highest yielding plant for a mother and take clones off her and then you can 12/12 clone from the time they root and get much more weight then 12/12 from seed since clones grow at a much faster rate!
hope that helps,
holla at ya boy