16 days from received to GRADED
GRADED for one week.
Even if shipped, tomorrow, would be approaching 25 days on a 15-day estimate.
If there is that much business that you are consistently 25-50% over on your estimated times, hire and train more help, and add equipment and/or space.
I am first time customer, and not impressed with turnaround times. Better to not estimate low, rather they should estimate high.
Under promise and over deliver.
Also, a complimentary email saying "We apologize for the delay on your order...blah blah" would be nice.