And I went with 12/12 right off the bat. I don't want the plants getting too big, so when they sprout a bit bigger, I'll tie them down. When will the plants start smelling?
Get your light as close as you possibly can without touching.
Doing this, you can veg for up to a month, and if you keep enough light and close enough throughout the grow, even after you flip, if you do some LST, you can keep plant height down under a couple feet (not counting soil) and you will be well rewarded with the increase in final harvest weight...... ESPECIALLY if you top once or twice!!!
Last summer, I did one, under about 300 or so watts of mixed 2700k and 5000k CFL's in a 2wx2dx4h closet, only vegged it for 28 days, topped once, and had it in a 5 gal. bucket, along with one other plant in a 2 gal. bucket in there, and got over 4 1/2oz. off her.
As far as smell, that all depends on the plant.
I've never been lucky enough to need filters since none of mine ever seem to smell as much as I'd like them to.