I basically use the 1k until it passes the thumbnail test. Then I 4k until it tree tops a few hairs. Move to 8k until it tree tops more hairs and more smoothly. Etc etc. I do that even with a loupe.

But, you gotta just do trial and error to find your benchmarks. I don't count strokes are anything, I just test every time I need to add water. I just kept scraping and testing until it seemed like I was no longer getting improvement on each stone.

Your razor looks great. Nice job.