Firing out a ceramic mould
AFAP is not recommended for ceramic moulds. Firing to about 720C (about 50C above the maximum slumping temperature) will be enough. Since I would be firing any glass on a mould no faster than 150C/hr, that is the rate i would use all the way up to 720C. No soak is necessary. Set the controller to “off” and let the kiln cool on its own from 720C down.
It is worth noting that in slip cast moulds there often is a “hard” spot where the liquid slip first contacts the mould. Normally, although it appears there is no kiln wash on the spot, there is enough to separate the glass from the mould. However the advice to fire the mould first before putting kiln wash on is a good one.