High thc possible means as few amber possible (thc degrades to cbn) unless you're also looking for the couch lock effect.
In the first case, you should flush your plants and harvest in 2 or 3 days.
And no prolonged periods in the dark as this will weaken the plant: after the last night, cut before dawn and let the plant in the dark half an hour before working on them.
This is more than enough time for the plant to return the sap to its roots and leaving the branches in the dark after pruning allows the sap remaining in the plants to set. If exposed to light too soon, the photosynthesis process will start and send the sap to the flowers (what this whole ritual seeks to avoid).