DPF regen cycles-how often, how to know & what to expect?

[LaurasOtherHalf]

Prompted by another thread where a posters mate thought his car was on fire I actually thought about it & if my wife noticed a load of smoke she'd turn the thing off & panic.

So, obviously in the need to educate her & with me never having ran a DPF equipped car what can she expect?

Car is a BMW X1 2.0 TD automatic

Is it something it does once a year, once every long run, how long does it take, if she turns the engine off too early will the gods of petrol exact their revenge with a huge DPF replacement bill etc etc.

[LaurasOtherHalf]

So it looks like she will never know when it's taking place then. Ah well, thought I'd ask...