Honestly that's strange being told that, I would be concerned about your choice of surgeons techniques if he honestly thinks it takes 3-4 weeks before you can return to work. It should be 1-2 weeks before returning to work. If you have to do lots of lifting then 2 weeks becuase heavy lifting etc increases the flood flow which can cause bleeding and also swelling etc. if you play sports where you could be hit on the face then you shouldn't do that for about 8 weeks because a trauma to your nose will affect your results.
But generally speaking, if your a student then you'll be back in the swing of things within a week but work wise from 2 weeks. No way will you need 6 weeks off.
The best surgeon I have found for this is Julian De Silva
www.londonfacialplasticsurgery.co.uk