Vegetation Flower

At what point do I change to 12-12 lighting. My girls have been in since 5/28 from seed. And about 12 inches tall.

let them veg for a good month before flowering

recommendation I have been given is let them veg till atleast 12" tall and have a minimum of 4 nodes. Plants will grow 1-2x their present height of entering flowering.

Nodes?. I am real fresh to this.. also I am wanting to move my plants indoors. What is the cheapest lighting for 3 plants in 8 qt pots. I don't have a lot of money to spend on this grow. I would like something around 100 bucks or less. Is there anything out there that will work?

iv read mainly that bigger plants will yeild slightly more best to wait till it reaches 20 inches in height

iv got 250w high powered sodium lamp cost me 80 quid fom hrponics shop or can get 450w for not much more however iv got small growin space and on a hot day can reach ocer 30 c in my grow room on most days tho roughly reaches 29 max so they can be a heatin problem but iv had no probs with my grow so far almost no troubles, metal halide costs round same but can get slightly warmer can also buy flourecents for cheap but there no way near as bright and will effect yeild positive sie is cheap to run and dont produce any were near as much heat!!

p.s was 80 quid for lamp with ballast and reflector

https://www.rollitup.org/cfl-growing/107992-tutorial-growing-cfls.html <--- Click

Cheapest lights for 3 plants in 8 qt pots

Also if you plan to keep them in 8qt pots and they're already 12in... you can start to flower them now as they probably won't exceed 2 feet without transplanting.

Ok so I am torn between sodium and CFL. Here are the stats of my grow area. Ok I will not have a/c unless a window unit is called for. So since I live in the midwest it is possible that the room could reach 100 F... I will have plenty of dark since there is one window and easy enough to cover. I will be suspending light from ceiling individually.
So I am open to all sugestions. As I am fresh here and really can't make up my own mind.

umm for with only 100 buck look into a 250 watt hps not as hot either. but dont expect the same results as a 400w

start flowering when ever u want!!!! what ever ur plants are height wise when u put em into flower u can expect em to atleast double in size.so carefull how tall u veg ur plants if ur growing indoors.

detroit has it right. Flower now if you like, you don't want to wait too long though because you might run out of room when your plants begin to stretch in flower