I stand corrected, sort of. The quote:
"We kindly ask that you allow at least two weeks from the date of your last submission for completion to occur."
My reading of this is something like, "please wait for a couple of weeks to call us and start freaking out that we lost something"
To me, that suggests that if it has been two weeks or more, it's probably not a bad idea to call, as I intend to do starting two weeks from today (today is the day I expect my last piece to arrive).