There is really no way to know--all you can do is put your best effort into it and see what happens. Six months sounds like a good goal to start out with.
If you have access to a physical therapist (especially one who works at/with a gym) that is definitely something to take advantage of as they can suggest just the right kinds of exercises to build strength and endurance in ways that won't aggravate your injuries.
Something that I did (and still do, actually) to extend the amount of exercise I am able to do is to alternate high-impact/weight-bearing exercises with non-weight-bearing ones. So if I do Zumba or run one day, I swim the next. I can't dance or run every day of the week, but I can do things like that 3-4 times a week and work in swimming on alternate days. Another way to do something like this is to alternate walking with riding a bike, either indoors or out.
Dances: salsa (standard/LA), casino, rueda de casino, cumbia Colombiana, bachata, mambo, cha-cha-chá, merengue, reggaetón.
Currently learning: Mexican cumbia, danzón, Cuban rumba
Dances to Learn in the future: flamenco, tango Argentino, samba, belly dancing, bhangra, ballroom rumba
| current weight: 213.0