i guess one thing I would be concerned about with plants that were fairly big in veg is that when they hit flower and begin their stretch, they get pretty big.. Stretch can be 2 to 3 times the height of the plant going into flower so... if your plants are 24 inches, count on them being say 48 to 60 inches tall.. that's strain dependent of course.. just a general rule I use to gestimate things. Topping, Fimming or Bending are pretty neat options to control the height though. It kinda depends on your ceiling in flower and how much room you've got to work with. You probably don't want them to get too much bigger though hey?
They haven't shown sex yet and judging from the looks of them, that's gonna be soon and I prefer to see sex in veg rather than flower cuz we usually pot up just before putting the plants into flower and why pot up a plant you will cull if its male?
So.. either way.. veg till sex, flower right away...it's your call and whatever you decide is a good decision.
