You can do it as soon as they root. Or veg them on 18/6 until you got the growth you're after then bud them. You're playing god for these plants when indoor its up to you.
once you've got some roots established on those clones its all up too you. veg em out or go straight to 12/12 just depends on the yield your looking for
like said i will just add to it lol once you get roots you can transplant into soil or hydro w/e you wanna do veg them out big or flip it straight off the bigger your plant the better yield if you have enough light to match it