Most of my punts are set up on the day. Some have been, with as little as 30 min notice (ie plan B, as I walked on plan A).
I don't often book in advanced and IIRC have only done so with 4 different W/G. Those were between 1 to 4 days in advanced, to set up a punt.
I also know, a chain of events can effect bookings and this is, a 2 way street!
IMO, it good manners (and courtesy) to contact a person and update them, in a reasonable time. If some thing does happens, that affects a booking.
No comms what so ever from her (even if you tried to contact for update). Also with the travel to a location, at that point (90 mins before agreed booking time), you may be late. Due to her fail comms.
Using that time, I would start researching a plan B. But I wouldn't book another punt (may be make some inquires). As double booking, is wrong IMO. After the agreed time, with out any update from her, I would just book elsewhere, (from the research, you may have done).
If it the case she blows you out and if you have the time
Please name and shame via a review!