When you arrange to meet her, tell her what time you're picking her up and tell her not to be late or you will honk your horn outside her place. If she's not ready when you arrive, you have every right to honk your horn, just like you said
She most likely won't be late because the social pressure of pissing off her neighbours will force her to get ready for you in time. It also makes you more in control, because she is forced to react and behave like a good girl to meet your schedule, not hers, this is exactly the frame you want, she has to be on time if she wants to be lucky enough to date you.Obviously, this means you shouldn't be late yourself so make sure you leave enough time to get there! If you're feeling nice, you could drop her a text saying you're 10 minutes away en route to make her rush her final makeup touches so you're not kept waiting.