need some advice...Please and Thanks

alright i have two clones that were vegged under cfl for 27 days 24-0 lighting and then were moved to my 600 watt for 20 more days at 18-6...
plants are about 15 inches tall, i just transplanted them into bigger pots today
my first question:
Would it be ok to switch to 12-12 tom?
i dont think the plants will be that shocked from the transplant i work at a greenhouse so im used to doing stuff like that.
second question is:
i have a 26 watt UVB repti light, how should i introduce that light to the plants like an hour for the first couple days and increase it an hour at a time from there on??
Third question:
should i hang that light above but across the tops of the clones?(hope you guys get what i mean) it says its effective up to 20'' so would that be the best way to cover the most top nugs?
Last question:
Im using fox farm nutes but only grow big and big bloom should i flush for a couple of days before starting big bloom?

If any of you feel like you could give me advice for any of these questions that would be great. rep for the best answers as well. heres a couple of pics as well... peace

i dont kno much about lighting but i can tell you u could switch to 12-12 rite now if you wanted

you can move to 12/12 when ever you want.
I used a 60w uv bulb on the last grow and left it on the whole time had mine off the tops about 6-8".
you could flush if you want but don't need to.

that plant looks nice growmigo. i think i would give her a day or so to get over whatever transplant shock there might have been before switching to 12/12

im not exactly sure what your asking about the light but my input is; it dosnt sound too strong of a buld so i would just use it when you start flowering

i would flush the nuts before adding new ones

Ok so im gonna switch to 12-12 tonight, im guess im gonna flush for a couple days since i got responses saying both... anyone elese know anything about the uvb??? i should prolly be getting another one soon so there will be two in there as well.