I had to do a lot of research to find out that there are no good templates to print. If you want a decent disc brake clock, you have to pay a lot of money. So I took the trouble to design a good open source one.
It is designed with low tolerances, so better print a little slower.
To mount the adapter just plug in the 6 holes of the rotor then just plug the clock mechanism on the back. Attach the hands and the clock is finished.
Also look here, a suitable stand with a great design: https://www.printables.com/de/model/221740-disc-brake-clock-stand-160180203mm
The author marked this model as their own original creation.