Actually the nodal point location depends on the aspect angle ( ß ) from the optical axis of the lens.
There is AN INFINITY of nodal points. They are located at a distance (D) that is about 17 or 20 mm (*) from the lens front to 4.5 mm from the same surface.
(*) In fact this experiment gives very satisfactory results for wide ß aspect angles. BUT when ß is small it is naturally difficult to accurately find the intersection point of the optical angle with the corresponding "Light ray".
As the most important range is for very wide angles and especially for ß=90 deg, then the process is satisfactorily helpful.
For a more accurate experiment result please go to this.