Flowering marijuana in a darkroom

From a fellow grower:

Hi have a 4 ft in dark room for 12 +outside for 12 flowering for last 5 weeks first how long to go and have fertilized it 4 weeks ago with osmocote + 1 week ago with thrive flower + fruit is that enough till harvest or does it need more.and also does it have to remain in 12 + 12 till ready or can it stay outside now till finish.never had lamps only dark room and outside is that alright.