vegging and flowering

if i veg with blue and red spectrum cfl's ,
can i flower with both aswell? as long as i switch to 12/12?

yes, why not?

well i was told that each spectrum is mainly used for each category, 1 for veg 1 for flower

Here it is in a nutshell. What we're all trying to do here is reproduce what happens in nature. The best light for plants is natural sunlight because it is white light, light that contains all of the colors of the visible spectrum (red, orange, yellow, green, blue, indigo, and violet). "Sunlight has an equal balance of the blue and red light rays that plants need. If you grow with both spectrums, you'll be reproducing the suns natural light better than just using one spectrum.

as long as i switch to 12/12?

Can a person veg with blue and red spectrum CFLs?
Yes

Can a person flower with blue and red spectrum CFLs?
I don't see why not , yes

How long till I should flower my plants?
Depends on your space. Plants will Double or even triple in size juring flowering