The rows of leaves ar called nodes. So your plants have 5 nodes.
There is no set size for a plant to be b4 you bud it as long as it has a decent root mass.
Just switch em onto 12/12 when they r a 1/3 of the size you want them to finish off being .
So like i said on another post if you have 6ft to play with switch em over at no more than 18" tall.
My grow space is about 36" in hight so all mine are switched over when they are no more than 6" tall and they all finish off being about 18" tall.