It really depends on how complex materials and how the lighting is set up how long the redners take - and how good quality you want, and the resolution aswell.

Lets say you can get a decent render in one hour per average:

1 hour x 24 frames x 120 sec = 2880 hours = 120 days = 4 months.... haha

On the other hand... of you can render a frame in 5 mins:

5 min x 24 frames x 120 sec = 14400 mins = 240 mins = 4 hours.

However 5 mins isn't a very good looking image...