There are two very simple signs. First, a warning light comes on the dashboard. Second, the car slows down and simply cannot reach a higher speed, however hard you press the accelerator.
That means it is time for cleaning. For passenger vehicles the machine procedure takes 90 minutes.
When a DPF problem appears, you can run a diagnostic test and check for an engine software update. A new filter is a major investment, so leave it aside while there are better-value options.
