With a cheap and simple eBay OBD dongle and the Torque app for a smart phone, you can eliminate all doubt if the vehicle is doing a regen.
Using Torque, EGT1 will rise to ~1150F and EGR will be reduced to ~0.
Also, the Bavarian Technic tool shows lots of info on the DPF status if you're interested in more data (soot and ash loading, differential pressure to see if its getting plugged, how long its been since your last regen, etc).
My car on my normal commuting schedule of 2x15 miles a day does a regen about every 400 miles. On long continuous drives its closer to 500 miles. Usually takes ~10 minutes to complete. With the BT you can even watch the soot level decrease as its getting burned off, which is kinda neat.