Lighting Advice needed: 24/7 or 18/6?

I have two g13 clones growing rightnow with 3 on vegging state and have 3 23 watts floro lights covering it about an inch away from the plants. they are showing good progress and with few yellow leaves on the bottom, which i was told not to worry about too much.

Should I keep lights on 24/7 or should i do 18/6 so plants get some rest?
I've researched a lot on this and have heard mix reviews.. what's the final on this expert growers.. I do want more bud eventually but i want my plants to grow right also.

I've had the clones for about a week, I will post some pics up later. they are decent heights. At what point, will I know they are ready to flower (12/12)

24/7. With weaker bulbs like CFL's, the more light the merrier.

thank you. anyone can answer the other questions pls?

How big are the clones? How long have you had them in the growing medium? The bigger the plant the more bud.

been growing clones for about a week.. they were already decent size when i got them.
I'll continue growing it for another 3 weeks or so depending on growth before going into 12/12