Just after you get your seeds to sprout and plant them in their first pots. Before flowering. The vegatitative state I believe its called, what is the length of light per day ?????? I know is not 12/12 (thats flowering). Is it 18hrs ? 24 hrs ? I have JUST started tonight with the seeds so need to know here pretty darn fast................. Thanks

It's a pretty heated subject that no one seems to agree on. you can use either one. here's a thread I started, you might want to give it a read.

which is better? 24/0 or 18/6 lights

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helpful links:
cfl-hps-how-much-light
el-cheapo-guide-lighting
drying-curing-your-buds
med-strains-specific-uses

18/6 seems to be the norm but some do 24/0 with out any adverse effects. suggest doing some more reading before grow gets much further along as more things are going to come up that you might have questions to.