The buyer will send the payment. After the payment is received in the Escrow Account, you will be notified and have to provide the buyer with the project data. You can give user/password to your ftp, so the buyer can download the data (Remember to backup databases if you have any) and verify it. After the project is verified the actual domain name transfer will start. The timeframe depends on the Registrar the domain name is registered at. After the domain name is successfully transferred, the buyer will confirm that he/she has full ownership over the domain name and you will get your funds.