This can very per kitty since all react differently. Is your kitty on an antibiotic like clyindomyacin?
For most kitties, when all the teeth are pulled, most of the inflammation goes away. From what I have read, sometimes there will be a slight remnant of the inflammation, and you still may require a round of mouth antibiotics once or twice a year. I would expect the inflammation to be mostly gone within a month, as long as you are giving an antibiotic too. Remember the tooth sockets have to heal in addition to the inflammation to go down.