How long does it take for your nose to heal if - 2 days after you got hit on it - it still has a bump?

Noses heal pretty quickly, but a serious wallop can take about a week, assuming the nose isn't broken. In the meantime, ice-pack it to reduce the swelling faster. You might also consider taking an over-the-counter painkiller/anti-inflammatory like Aspirin, Acetaminophen or ibuprofen (naturally, always follow the directions on the box and don't take these if you have adverse reactions to them).

If you think the nose may be broken, it's worth getting an X-ray. If a broken nose heals incorrectly, it may cause nasal breathing problems for life.

If a bump stays for even longer period of time, you should definitely go to a doctor.