Usually on the plans the thrust line will be drawn on the fuselage. This line starts at the front and extends to the rear of the fuse and is the datum point for incidence set up.
All incidence and thrust settings are derived from this line.
Your plans may have the incidence built into the horizontal stab. Some are other than 0 degrees and you can use the side view from the fuse to determine it.
If you look at the side view of all the flying surfaces I'm sure there will be a datum as to the incidence.