i ran a test with one of my plants a couple years ago just in case i had to do the same thing, at the time i was doin some major remods on the house. i stuck a plant that had been vegging for 3 weeks in a dark cabinet, just gave it water every once in awhile. after 3 or 4 days the plant started to turn a pale yellow at the top. after 10 days pretty much the whole top half of the plant was a very pale yellow but other than that it looked healthy. i threw it back under the light on the 10th day and after a few days of light the plant was back to normal...it greened right up, never threw any pre-flowers. you'll be good.