Question on supervised visitation?

Hi I think my ex will be getting supervised visitation of our girl. My question is how long does this set up usually last before he can take her alone. Also how dose this work with holidays and birthdays? how is the place of the visitation determined? and how is the supervising person determined. As the custodial parent how much say do I have in these things? THanks (please only answer if you KNOW!!!)