Ask fast, because the memory is short
A buyer who bought a television three weeks ago still remembers buying it. A buyer who bought a case of olive oil three weeks ago has bought four other things since and has no particular recollection of your listing.
This is the single biggest difference between grocery and everything else on this site. Everywhere else the advice is to wait — for the product to be used, installed, worn or tested. On Carrefour, waiting is how you lose the review. The purchase is low-drama and it fades quickly.
The right window is short: soon after delivery, while the buyer can still picture what arrived and how it arrived.
Repeat purchase makes a review a recommendation to yourself
Grocery is a category people buy on a cycle. That changes what a review is doing on the page. A buyer reading reviews on a pantry staple is not making a one-off decision, they are deciding whether to make this their default for the next year.
That raises the value of every review disproportionately. It also means your reviewers are frequently your repeat customers, who are the buyers most likely to write something positive and specific — if anyone ever asks them.
The review is partly about the delivery, and you should want that
In most categories a review that talks about packaging rather than the product is a weak review. In grocery it is a strong one. Did the box arrive intact, was anything crushed, was the date code good, was it packed sensibly — these are exactly the anxieties a grocery buyer has about ordering from a third-party seller rather than from Carrefour itself.
A seller with twenty reviews saying "arrived well packed, dates were good" has answered the objection that was stopping the next buyer.
What Merita does
We watch your Carrefour orders for delivery, ask promptly rather than late, and send one message in French through the marketplace's own buyer messaging. Nothing is offered in exchange. Orders with a complaint, a refund or an open return are excluded automatically.