I usually show up about 30-40 minutes early. My therapist commented on it once, I explained that because the office is so far away and my appt time is just an hour after work, I don't want to just wait around and kill time for 20 minutes only to get stuck in rush hour traffic. If I waited, the rush hour traffic would make it a longer, more annoying commute. I'd rather just drive to the office and wait outside, read a book, make notes or get a tea and collect myself down the street before session.

For me, however, it's not really about fear of being late. If my appt were on a Sat. I'd probably time my arrival a lot closer to the appt time. Google Maps is great for this, btw. I know the directions but I love using the feature to tell me when I should leave by to get somewhere on time.

I don't think the idea of 'testing' late arrival is a bad thing but I would just make it about 5 minutes, not ten. That eats into your paid time.