What goes wrong
Use the pack count from the last clear week of that size.
Packaging Boxes lists Single wall boxes for this line. Reorder the sizes you packed, in the quantities you packed.
The check before you reorder
The reorder is the dimensions and single wall.
Store sizes in columns. The print on the bundle is the size. The end of the bundle is not.
Dispatch on that order
A Friday order on Packaging Boxes that includes Single wall boxes aims for Monday. A bank holiday on Friday or Monday moves that delivery. The 3pm cutoff is still the same-day dispatch rule.