He is probably talking about priority mail, the package / postage are a single fee. With regular postage you are correct, they charge you for a box.
Yea, I’m referring to the priority mail boxes. However, by simply cutting the box and re-taping it with the inside-out, you don’t have to ship Priority Mail with them.
Doesn’t matter to me really but if I had to state a time I would go with after 5PM EST M-F or over the weekend.