I have a 2006 A4 1.8t cabriolet with 74k. The Euro repair shop told me the timing belt would not need changing until 100k. I specifically asked the repair shop if that was correct because I was seeing 75k. They assured me 100k. Trust me these folks usually have a recommended repair everytime I show up for oil change. I have spent some serious cash betweeen my car, spouse's car and motorcycle in the last two months. So I am hoping 100k is the correct interval.

 

This topic has been discussed to death and let me give you my advice since I can relate:

My car 05 Tip Quatrro 1.8T with...25,000km!
My dealer told me i HAVE to do it regaldless of mileage since they recommend 100k or 125k and or 5 years whichever comes first. They charge $1500
My independent Audi shop would do it for around $700/$800 wich includes Timing belt, tensionners, Water pump, rollers...etc

You can wait until next summer however when doing your routine maintenance have them take a look at the condition on your belt (cracks...etc) keep in mind that most of the time it is the tensioners and water pump that break first causing major unwanted damage!

Hope that helps!