The first day, I noticed how really BAD a cigarette smelled, but really took about a month before I started noticing any big improvements.
But I work with some mean solvents, glues, etc., so probably I am still not totally rejuventated. One of the things I first noticed were our closets. Didn't take long to get some extra laundry going. Then the curtains, then the ceilings and walls, then.....well, you get the idea. Coming in from outside fresh cold air, my house finally smells nice! Sort of like caramel in some corners. Funny how you don't think about tastes and smells until it comes back. It is amazing.