wait to put them into flowering until your plant(s) preflower (if you don't know what preflowering is, check the boards, there are lots of great pics on this). preflowering should occur 2-3 after your seed has sprouted, in a healthy happy plant. pistils=female, balls=male. you want to wait for them to preflower, before you switch them to 12/12 because the preflowering means that they are sexually mature. if you put them into 12/12 too early, the plants will usually wait to flower until they are sexually mature anyways, ie. putting your plants into 12/12 too early won't make them flower any faster than if you had waited for them to preflower.