If you're a seller on Fiverr, then you have to wait until the client left feedback on your order. Otherwise, you won't be able to leave a review as a seller. But if you're a client, you can leave a review after accepting the delivery. You won't be able to leave a review without accepting the delivery. So if you want to leave a review, go to the order page, accept the delivery and look for a feedback option at the bottom of the delivery. Fiverr will ask you to leave feedback for 3 specific fields: communication, service, and recommendation.