sheist.. it really deppends on the strain and the gentics...

some plants will do fine under those conditions..
http://boards.cannabis.com/showthread.php?t=48343


one of these plants on the thread above was flowered when it was 15-17 days old.. started from seed...

And it turned out awesome..

SOme plants will not flower even when they are put to 12/12 if they are not mature.. meaning they don't have pre-sex or alternating nodes...

: )

If you have the resources, it is very fun to experiment wth the plants.. both seeds and clones...