Ah, waiting for the return call. Usually, by the next day they call. They call after they've seen their patients for the day, if not inbetween appointments. As for an opening to be seen, I wouldn't know but hopefully within just a few days, she/he can see you.

If she/he hasn't called back after a day and a half, I would ask your mother to please leave another message. Maybe something prevented the first message from getting through.