How long should I wait to return to work after having a major hamstring rupture?

Depends... Should be directed by your surgeon and therapist... Dont try to speed up the healing process. Listen to your orthopedist! The post surgery/ rehab period is very very important for the complete healing process! Best to you!
Depends on your work. If a desk worker and you are not having surgery, then you likely can return within a few days, although sitting may be painful. If you have a more rigorous job, then it may be several weeks. Full recovery from a grade iii hamstring injury is usually in the 6-12 month range.