Sounds risky to me especially if the drywall is on the sides of the vanity. Why does it have to be in this order? Can it be retemplated after all is done for a final template?

Durhams Water Putty???

The mention of home button may have solved a problem. I mentioned this before, but when I talked to the apple tech I asked how to quit an app. He told me where to swipe. But he never told me how to close all the apps and I figured swiping must have closed them too. When I read about the home button, my iPad Air 5 doesn't have one so I googled it and yes it does! I haven't had time to do it yet but I'd go to settings, and other many steps, and there is a round circle like a home button, which will appear on the home screen. It can be moved with my finger to put it in a place I want. And I can move it again. That's the home button. Hit my head on the wall! Then I tap it twice to bring up open apps to close. Biggest world mystery, of all the money apple has made off us, why can't they put a quick start sheet in the package?

You don't necessarily need local, but you do need math. At your wall, measure 3' to the left from the corner and make a mark. Measure 4" to the right from the corner and make a mark. Measure between the marks; you should have 5'. Any deviation from 5' is how far your walls are out of square. Relay this information to your fabricator and have him build the top out of square if necessary. Remember, if your cabinet installer was any good, he installed the cabinets square and in plane to each other. If you want consistent overhang, this information must be provided to the fabricator as well.