Best way to transition to flowering?

Hey all. We are about 2 months into a soil grow under a 430W HPS. Plants are 2 1/2 ft tall. Been using the GH Flora series supplemented with diamond nectar and floralicious grow.

The GH feeding schedule shows a transitional period from veg to flower. So how long is the transitional period supposed to last? Should I change the lights to 12/12 right away? Or should I skip it and go straight to flowering?

Any and all help is appreciated.

I have never used a transitional period, but that does sound interesting. My opinion would be to just switch to 12/12.