Count the job, not the habit
The weekly count is the slim line that was packed this way.
Count that line only.
Where it lives during that week
Keep them flat and separate from book wraps.
Order M-envelopes on their own line.
The reorder line
Say M-envelope and the size.
At Packaging Boxes, M-envelope boxes does not change the cutoff. Orders by 3pm leave the same day. Under £50 ex VAT the delivery is still available. It is just not the free threshold.
Open M-envelope boxes when you already know this line. The page shows the pack quantity. Packaging Boxes will still dispatch an order placed by 3pm on the same day.