if i were you, i would top those plants, order the 400w, when it comes, put it up and set 12/12. you don't have much branching, but they are getting tall, thats why i suggest a top, or you could set 12/12 now, order you're 400w and when it comes, put it up right before the light cycle, i did this when i used cfl's. the reason i say flower now is with the 400whps it will flower your plant amazingly well, but only the top 15-20 inches, those plants will double to triple in size the first 2 weeks of flowering, and that penetration won't do, they could branch out during flowering.... ive seen some plants not. the decision is your's, just trying to give you some expierence from something i learned myself.