Well I'm only a first time grower myself here's my log: http://boards.cannabis.com/grow-log/...ndow-grow.html

You can go 12/12 any time after 6 weeks veg really, I've read cases of ppl going 12/12 from germination but obviously the bigger the plant is the bigger the yields are. Mine are a little over a foot now, a bit higher then I'd like really, but I'm not complaining. I'm thinking you should start flowering, if you carry on vegging you run the risk of flowering into autumn, I'm no expert and you should probably ask around first but i don't trust our weather i just wouldn't want them to be sitting in a coldframe come September you know.