This is my thrid entry trying to find out information about zippers. I am new to the website and is still trying for figure out where to put what! My question is exactly where do you start on the unlapped side of a lapped zipper? Is it in front of the zipper stop, behind it or beside it?

I love lapped zippers because they completely hide the zipper, but there is a part of the construction I am not sure about. Exactly where do I start the unlapped (hope that is a word) portion of the zipper. Is it just above the zipper stop, below it, aligned with it....Where? I'm introducing my grandaugher to sewing and I want to make sure I give her sound advice as well as get the answer for myself.