Those are for making holes in mild steel breaker panels when you don't want to be drilling. You have to sandwich the metal with the punch, something that's clearly not possible with an installed sink.

I would also use a drill bit for steel rather than the holesaw, but I wouldn't bother to step up the bits. Easier to just start with the desired size bit, as wear isn't issue with one hole thru sheetmetal. That lets you drill one hole and you're done.