It should say in the handbook, as there are different times for different 2.0TDI engines (PD and CR).
There's been a lot of discussion on this in previous threads, but if you stick to the 70,000 miles or 5 years rule then you'll be fine.
My handbook says 133,000 miles (215,000 km) for the 2.0 TDI common rail engine. I checked with Audi and they said 70,000 miles. When I questioned them about the fact that the book says one thing and they say another, they went off and contacted Audi. They came back and said yes, 133,000 miles is actually correct, they just use 70,000 miles for all models across the board. Obviously this will mean that some will be changed earlier than they need to, but they use the better safe than sorry method. Clearly money for the dealer has nothing to do with this.
As it was, my water pump developed a leak at 71,000 miles so I ended up getting the belt changed then anyway.
You'll probably find the belt is good for 133,000 miles, but the water pump isn't.