Need advice on going from VEG to FLOWER

I will post updated pics a little later but at least one if not both of the plants you see below are about ready to flip the switch and go to 12/12.

So my big question is what preparations should I make leading up to the switch? Should I change my nutrients now before I change the lights? I am using the Fox farms 3 nutrients combo so I would assume I go from the Big Grow over to step two of Tiger Bloom.

Any other tips or anything I should do?

Any help is appreciated as this is my first grow.the pics you see in my link are about a week old so they are just growing very fast.

just reset your timer and go for it.

I normally leave my plants in total darkness for 36 hours, this normally speeds up the transition phase.

You cant flower those plants yet. They are not sexually mature. If you flowered them at this point they would probably triple in size, but would not yield much if anything. You need to wait for at LEAST 4 to 6 weeks of vegetative growth to take place before your plants are mature enough to complete the flowering phase. They should be at least 18" tall if not much larger when you make the transition to 12/12. I usually Veg for at least 8 weeks at least before I flower unless I'm starting from clones, if you do it any sooner you will not yield very much. Ideally you should wait until you see the pre-flowers emerge before you make the switch.

As far as the actual transition goes, you don't need to do anything fancy. Just set your timer on 12/12 so that the lights will be on whenever is convenient for you to go in there and water and stuff. You don't want to expose your plants to any light during the dark phase. You can start the bloom fertilizer on the first watering after the transition.