If we haven't had our court date, can I change my mind on our agreed visitations?

It is a little unclear what is going on here, but I am guessing the other party made a request for an order including some sort of visitation and you filed a response not opposing it, but now you do.

If you haven't had a court date and haven't signed a stipulation (agreement), then you can go to the hearing and tell the judge you now oppose the visitation requested.  Also tell the mediatior at the mediation that you oppose the visitation.

Best of luck.