nutrient question first timer

I'm growing under a 400 Watt hps with indicas and some satiava. My medium is soil. I've been using General Hydoponics Flora nova veg. mix and I'm planning to buy the flowering mix. I think I'm ready to flower. most of my indcas are about 24" and my sativas are around36"-39" but nothing I'm reading tells how to Shift from one type of nutrients to the other. Should I flush with water for a while or should I just go straight to the flowering nutrients. When I go to 12/12.
soryy this is so long I don't Know what I'm doing and all my freinds are to stupid to help.

Yeah just use the nutrients, but dont use full strength, use 1/4 of what the bottle says to use then gradually build up... say 1/4 the first watering, 1/2 second, 3/4 on the third watering & on the forth go full strength.