I have come to read that "en route to the printers" message as "the file has been checked
by a human and a cnc job file for the printer has been created, so no worries that it might
still be rejected". After that, I guess it is waiting in line with all the other preprocessed jobs.
So far, my orders have been shipped either on the estimated date, or 1-2 days in advance.
(There must be some slack in the estimation to account for hardware problems, occasional
misprints, workers calling in sick or whatever little mishaps you would expect in what still must
be a small business by headcount)