Give them time, if they've taken root then it won't be long before the roots pop through the rockwool.
Why not use the plant you took the cuttings off as a mother plant so you've got a constant supply of clones? I would keep it under 24 hours of light permanantly so I always had a source of clones.
If your cuttings have taken root then you could start flowering them but you could let them get a little bigger first.
If you do use the plant as a mother plant then by the time these cuttings have finished flowering, the mother plant will have lots of new growth so you can take more cuttings. it just goes round and round like that, a cycle.
What breeder is the K2 from? is it Nirvana?

Hope this helps Burdo

GC