On my physical disk I just made a marker with my pen. I would advise against making a snap-lock point as that might disrupt any calculations when you are not needing that specific point. It could result in incorrect calculations involving time because of the snap.
Instead I would suggest to change the template to emphasize that point. Useful points are imho: 180/pi seconds (57.3 on the orange Zeit disk; or 9m33s on the minute scale) Align distance in the turn on the distance scale to the angle turn shown as seconds (not minutes!). So a full 360 degrees turn is 36(0) seconds marker or the white 6th minute marker. Then the 180/pi marker points to the radius on the distance scale. Check 6283m to 36(0) seconds and 1000m as radius at 57.3 marker.
Similarly as I suggested OneLifeCrissis back in the day for the speed calculation and zoom-factor correction magic-number on the RAOBF)
Also, there is already a Pi marker at 3140m on the distance scale, and 3.14knots on the speed scale. I haven't found a good use in calculations for those though.
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