If possible pre-drill the frame for the fixings - try to make sure that your fixings are going to go into solid masonry rather than mortar, and make sure to avoid where the hinges, lock plate, door closers, etc are going to go. Position the through the frame in the hole. Drill through the frame with an SDS hammer drill for the first fixing and clean out the hole properly. Make sure that the hole is deep enough and that it is cleaned out properly! Push the fixing into the hole as far as it will go, pack the frame out as required then smack sharply with a hammer to knock level, protecting the timber with an offcut if necessary. Level the frame and repeat on the other side. Then proceed with the rest of the fixings. Large exterior door frames I give three per side to and two at the top unless it's a steel lintel.
Scrit