Seems like unfortunate set of circumstances. If you wanted 11am meet then you're running the risk of things going tits up without her validation.
She could be taking dick till 3am and needed a rest?
Say your appointment was 2pm, they'll be time to confirm before you made the journey.
I've have girls say they start at 3pm and don't answer until 5pm.

lucky I just pack some sandwiches and wait for them

(jk)