PLeisure is right of course in that only the escort can confirm the appointment - but you can still leave feedback for her. you just can.t "rate" it (positive or negative) however your (max 3 lines) comment will still be shown as "feedback only".
If you look at any escort on AW with a fair bit of feedback you will probably see most that are rated "positive" but a few that say "feedback only" - these don.t count towards her overall rating number ....for example 20 positive and 1 negative will show her having a rating of 19, irrespective of how many (and whatever the comment) in "feedback only".
Hope this helps.