If you are in a food delivery business, it doesn't make sense to me to ask for a review just after the order is marked as completed by the delivery guy.
(Why would I give a rating when I have not even open the parcel and tested the food?)
The best way would be to trigger this via push notification after like 30-40-60 minutes after the order is completed. (So that by that time the customer have enjoyed the food)
Another good way is to show a block on top of the footer on the homepage after 30-40-60 minutes and ask for the review.
And the best way I have seen is just ask for the review for the delivery when the order is completed, and for the product review wait for the customer to consume the food.
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Guys please discuss the possibilities and suggestions and best way of implementation rather than just posting +1 +1 +1