To my knowledge, the TS 55's fine depth adjustment is designed as a trial and error feature. As a consequence, there's no scale which could help you to determine the settings.
I was told that the fine depth adjustment is primarily used by woodworkers who replace damaged pieces of parquet floors. They set the cutting depth stop at the cutting depth they expect to need, perform a cut, fine-adjust the cutting depth, cut again, check the depth, fine-adjust again if required etc.
Hope this helps,
Christian