don't flush and just cure for 2 months, the plant will still be alive after it is cut and use up any lingering nutrients until it is dried and then it's ready to smoke.
dont just go by dying leaves, all my fan leaves were gone 3 weeks ago due to flowering and it's almost done now, if the top buds truly look ripe than you can harvest those now and leave the premature buds to finish on the plant.
I left my plant a week with no light and just watered before i left and it was fine, grew alot in the time i was gone too..dont over think it, you dont want to come home to a fire...
get a ziploc bag, place seeds in wet paper towel(not too wet) and throw it in there then blow your breath into the bag, seal it and put it in the dark for 4-5 days.