Only in vegging and early flowering ... ideally in vegging. BUT ... you can harvest by cutting the plant way back, leaving a little green on the bottom, and then reveg. After harvest, turn the lights back to 18/6 and proceed just like you are vegging her out. The plant will start new growth within three weeks. The new growth will look really weird for a while, but will grow out of that stage. Once she is vegged nice and healthy, take your cutting at that time.
Vi