The only thing I would add is to make sure your start with the recommended filter pack.
Staring from no filters you will be printing a fair number of iterations to get close to true colours.
The other thing that the device can fail by is what is know as 'subject failure'.
Most scenes shot outside will integrate to grey when diffused.
Scenes with a large preponderence of one colour do not integrate to grey.
Your best tool here is to make a habit to shoot a grey card on the film you work with, and project it to calibrate filteration.
When I started to print my own colour I shot a grey card on each different type of film I shot.
It need not be in focus, but should fill most of the frame.
I would hold a 4x5 grey card dragged from the camer bag out at arms length, and let light fall on it the way that the light was illuminating the rest of the frame, usually mid day pointed towards the northern sky.
No diffusion is needed when analysing using a grey card as the negative subject matter, other than you should to account for light fall off in the density judgement patches that presume a diffuser is in use.
You then have the actual grey card colur reference to compare print hues against as an added check on colour.
It sounds rinky dink, but shooting a grey card with each film is actually a powerful tool to help you learn to print colour a lot easier.
Also be aware the dye colours in the calculator may have shifted though the years.
I have two of these; one by Unicolour and one by Kodak, and they disagree by about 5-10cc in a couple of directions of filtration but not in others.
