Don't you love it when you do "special" for a client and they take advantage. This is why I don't do "special" for anyone anymore. Since it is within a 5 min. give or take, I just would not open my door prior to 7:45am. Let her knock for 5 min. I would ignore it. As for arriving late...I would hand her a late payment fee even if she's 2 min. late.

Hopefully your client will "get" it and stop trying to squeeze in an extra few minutes here and there.