making the photperiod switch?

I have 1 violator kush, 1 white berry, & 1 ak-48 @ 3 weeks veg. They are all about 12" tall and I just started the dark period this morn... Has anyone noticed a difference between 24 hrs & 36 hrs dark to induce flower? These are all femmed so I should be good on sexing, fingers crossed. What experience should I expect to have from this time on [flowering] with these strains? And finally, can I go all the way through the grow without a carbon filter? I am willing to spend a ton on ONA if necessary, just need to keep smell contained in a 8' X 4' closet..