If they don't have to do too much work other than removing the spur, your recovery time shouldn't be too long. Obviously, there will be an inceision and stitches which will come out after ~2 weeks - so you can't do much until then. Again, you could probably start being more mobile and start to think again about running after ~3 weeks. All of this really depends too on the amount of swelling that occurs too ... another thing, if your doc says that it is OK to run afer 3 weeks or so, you might need to use something to keep your shoe from rubbing against the spot where the incision was made. Regarding swelling, some people have virtually none, others have a much more difficult time.
If they have to do more work, clean the joint, resection, etc - plan on a much longer recovery time. I can tell you all about that. ;-)