When should the timing belt be changed?

My automatic transmission light doesn't turn on when you turn the headlights on. Can't see what gear its in at night.

The recommended mileage is 90,000 But if it is original it may be starting to dry rot, which is when the rubber drys out. You should be ok for now:)

Simple answer. NO a timing should be changed every 50,000 mile's. It may last a while longer on a newer car but it is not recommended Your timing belt is 10 year's which is cause for concern regardless of the milage. Snapped timing belt new engine. Hope this helps. Cheers

Most timing belts are have an average life of 60000 miles. I would recommend everyone to have the timing belt changed when it is due to be. the alternative is a tow bill, sometimes internal engine damage can also result from a failed timing belt. How much money do you really want to spend?
Btw if the water pump is run from the timing belt, consider having this replaced at the same time or when it does fail you will wish you had done it with the timing belt replacement in the first place.