Except that buyers have the option to defect a seller if the item is received later than eBay's guesstimate. And it is very much worded as a survey. A few of those would see the OP in trouble.

That's for non-tracked parcels.

For tracked parcels a delivery date or lodgement scan outside of eBay estimates or seller handling time is an automatic defect, regardless of how understanding buyers are.

With the way eBay is these days it is best to cover your backside where possible.