I'm trying to think of Scripture where the person was baptized prior to belief. I think that in all instances those baptized were adult believers and it was done after a profession of faith.
Of course. Why would an adult be baptized if he/she didn’t believe? That might even be classed a sacrilege.
Acts 16 mentions someone’s “entire household” being baptized. That may well have included young folks—we’re not sure but it’s possible.