Pull the fabric until the folded edge lines up with the 0 inch mark on your ruler. (thehyperhouse.com)
The lower torso when fixing the strap position should be below the usual 7 inch mark in order to fit correctly (babieslounge.com)
Without being at home to check I would guesstimate the heels are around the couple of inches mark — I will report back when I'm next in the same building as them! (cici-marie.com)