Putting boxes in the fridge before the freezer accustoms the beetles/eggs to the lower temperatures. It increases their survival rate in the freezer, forcing you to extend freeze time by days.
Human bodies are ~70% water, cigars are ~13% water, freezing doesn’t affect them in the same way. Cello WON’T stop beetles, they’ll bite right through it. I’ve seen it. Not sure if Boxes will stop them either, they can probably burrow through soft wood or escape through tight spaces.
For what it’s worth, I freeze everything other than FOH boxes. Box goes directly into the freezer for a week, then counter for half an hour, then into humidor. If every exported cigar is frozen, then freezing won’t change the flavor in any way, it’s already been frozen before!