If the vet said 18 hours of dark and 6 hours of light then do that. Don't put her in your room or some other "not dark place. Keep food and water nearby or in her box and keep it dark. Dark as night, but not necessarily a moonless night. She can and will eat PLENTY of food in the 4 or 6 hours...
the3ofus+oursixchicks :
do yall think i should do half of it in the morning and half in the evening or, all at one time?
Absolutely all at once. The idea is to get her to stop laying by replicating short days and long nights. Shortening both day and night like that would be confusing.
the3ofus+oursixchicks :
i want to try to get a little off.
If she's passing poop then her vent isn't blocked. If her vent isn't blocked don't pick at it.