I give clients 30 mins after the scheduled time.

Here's another recent discussion:
How long do you wait? Provider late for a confirmed session.
Posted 10/12/2015 at 5:52:30 AM
WilliamKidd

15-30 is the general A to the general Q.

Specifics can shift things a little, depending on your own temperament and schedule ("I gotta get back to work at 3:15, not 4:30!!!" "I'm going to a party with friends at 10, not 11:15!")

- A phone call or text asking you to wait another 5 minutes buys her another 15 minutes. At least you know she's there.
- NOT ANSWERING OR ACKNOWLEDGING your calls or texts is a very bad sign