nooby question

i have a plant about a foot tall should i leave it at a 24hr light schedule or a 12 12 help? ?!?!?

you switch to 12/12 when the plant is half the size you want it to finish, or until you don't want to wait any longer. your choice

Actually depends on the strain, dank lover.

My preferences are the following:
I always wait until they have 6-8 internodes. For indicas, i prefer to let them reach 8-12 inch, for sativas, i prefer 20-24 inch. Indicas tend to double their height during flowering while sativas triple or even quadruple their height.

You might also want to know that 18/6 will make a plant strechier and taller while 24/0 will make it bushier and smaller.