Help a newbie with lights

I don't like buying cause I don't really know what I'm getting, so I'm gonna grow. I understand light for vegatative growth should be above 5000K and for flowering around 2700K. Do I use one set of bulbs for the first stage and another set for the second stage? Or should I have both spectrums at the same time for both stages?

im not a cfl grower but i would think having both would be benificial to the plant. of course you could just use one set of lights for each stage of growth.