Lol ok ok ok. I was reading that the denim is vanity sized and run bigger than normal jeans. So most people who buy rock em 1-3 sizes down from their true size. Even the store says if you're new to buying size down.
APC is a raw denim. Raw denim has no stretch when you first get it. As you wear it over time, the denim stretches. APC generally has a shorter stretch time than other raw denim so it will stretch out fairly quickly (a month longest). What you were told is correct, but not that great of a change. I'm generally a 32, but a 31 in APC.
If you are a 40, try a 38 or 39. Just make it so you can barely close the button, then they will stretch out perfectly. I would try them on, however. But by no means get a 36 if you are a 40.
And get the New Standard. With your waist, they are the best fit.
Edit. I just saw the question was to a specific APC jean. My advice still stands, but those jeans look really, really tight. Good luck.