I would invite her for another dinner: which day is good for you, Wednesday or Thursday? You don’t have time any other day, you are extremely busy for the next 3 weeks (you have to wash your socks and so on). This way she has to choose one of those days, or flake. Call is probably much better than text, if she doesn’t pick up leave a voice message.
If she goes push things forward, don’t worry about what she says about her previous BF. You don’t want to be her friend who listens to her complaining about that great relationship she had. You don’t want to give her wonderful time when you are listening while she is complaining. No, you want to be guy who shows her much better time than her old BF.
If she doesn’t go drop her, there is nothing you can do. Don't call, don't text, don't contact her in any way. She is probably still thinking about her BF, and maybe just “looking around”, and you are one of the potential replacement. Either get in quickly in or get out fast, you don’t want to be her orbital or great friend…