Just fitted a new Baumatic ceramic hob in a kitchen we were renovating. The fitting instructions give the cutout dimensions which do not take into account the screws sticking out from the side of the hob.
Here is our first attempt to drop the hob into the cutout made to the size specified in the Baumatic instructions. As you can see the screws in the front of the hob are preventing the hob from fully seating in the aperture.
Here is the cutout marked up for the extra cuts to allow for the screwheads. Note also that the instructions state the the air holes in the side of the hob should not be blocked which would be the case given the cutout dimensions supplied so we have marked some extra channels to allow for these.