12/12 from seedling

hi on my 2nd grow and ive been reading on the net that it is possible to go 12/12 from seedling. obviosly i realise that my harvest will be as low as an oz per plant but im wanting before xmas,hence the rush.
my seedlings are 3 week old,picture hopefully attached.
i was wondering if anyone could give me advice on this subject plzz?
strain nirvana northern lights
250 watt hps

Start on 12/12 now and just keep going until harvest all your doing is taking out the veg stage

You will likely get less than 1oz per plant as its gonna be one small bud per plant... but if yr in a hurry i say go for it