I put other. Usually it's about one minute. I come into the waiting room, sit down, take my headphones off, put them away. At that point I already here my T closing his window or washing his coffee mug, and by the time I'm done stashing stuff away he's coming to the waiting room. On rare occasions it's two or three minutes, if he has to use the bathroom or is busy. He's never made me wait more than five minutes.

I usually arrive around 10 minutes before my session would usually start and it most of the time seems like he is just waiting until I pop in. I think if he didn't show up for more than 5 minutes after my appointment time, I'd go knock... it would be very out of character.

Edit: for other Ts I have waited for up to 30 minutes. It bothers me a lot though and it's a reason why I dropped those Ts. I have other places to be, if you tell me to be there at a certain time, I expect the same from you. Time management is an important part of a Ts job and is not that hard that I have to regularly wait more than 5 minutes.