There is no exact measurement, but it should be close to that edge, yes. Doing so should make it look like the reference photo. 

https://imgur.com/a/6Aw32J7 Here's my progress so far,I'm pretty close just need to finish weathering greaves,ab,shoulder bell and make a few little adjustments. I was uploading through imgur but seem to be having trouble lately it's saying the file is too big still,so sorry about lack of pictures 

Is the slit all the way to the inside edge of the indentation?

Thank you. What about placement?

Check these two photos from our Scoutopedia, below. The slits need to be just long enough and just wide enough to fit the 1.5" strapping. Beyond that, there are no specific measurements given.