The WW seeds I got from Nirvana last year are about 12 weeks from seed to harvest. You can definitely go longer as they will continue to branch off and bud. I'm in a hurry, so I usually put them on the twelve hour cycle after about two or three weeks. With my LED/UFO - CFL setup, mine stay pretty short with this method, maybe 24 inches. My friend has a 400 HPS and he gets high productivity with these same seeds, even with a short veg cycle, and his will get much taller and fuller. BTW, if you get a male, the resulting seeds to the same WW female are really good. I got over six hundred seeds in my last seed project. These are fairly consistent quality and usually get at least 66% female. I've found if you go for seeds, pollinating the exact same breed with itself will yield pretty good results. When I cross with a different breed, I get bad results usually.
Especially if you have a decent HPS, over vegging is kind of a waste.