Whenever I drive my car, apart from observing the meters on the dashboard, I will also try to hear if there is any weird sound coming from the bonnet. Chances are that I will hear the sound of the timing belt flapping against the plastic casing. If this happens to you, then you will have to open the bonnet and check the source of the sound. If this is the case, then the belt needs tightening at the workshop. But what I dreaded most is when the car stalled when the belt breaks. So far this has happened to me just once and it was a very costly break.
The crankshaft is connected to the camshaft by way of the timing belt. With the belt in place, the crankshaft can then drive the camshaft which will allow the opening and closing of the valves. If the belt breaks, the valves will open at different times and then be struck by the pistons. Often the pistons will crack or break. This is very costly.
So you will have to monitor your car properly just in case the belt is worn out or just about to break. Normally your mechanic will advise you accordingly as to when you should have the belt replaced. Normally, the belt is replaced after running the car for about 100,000 kilometers.
I would rather make sure that I send my car for servicing every three months or 5,000 kilometers whichever is earlier. Then the mechanic will advise you accordingly on the life span of the belt. The rest is up to you to monitor.