Oh hon I empathize with how frustrating that is ~ I think sometimes poeple assume since we are just 'home' it is no big deal to arrive early or late not realizing how planning and organization WORKS for us

I would definitely talk to her about how you are feeling and make it clear that if she is going to be late specially after having made arrangements to arrive early that it is respectful to notify you otherwise you will have to reconsider allowing that flexibility because being left waiting for 45 minutes expecting a child any minute is not fair!

I know myself there are many things I do in the morning to prep for the program so if I am expecting someone any minute for arrival I would not 'start something new' until after the had arrived so I am not caught in the middle of kneading dough for buns or stirring something on the stove or something when they arrive and having it get ruined!