We will meet at Ul'dah Aetheryte Plaza. However, in some cases, I may need your help to travel to the OC region. Log out -> Back to your main menu => Data center => Select Materia => Pick any server (needs to load for the first time) => Then return to your main character selection screen => Right-click => Select "Visit Another Data Center" => Select OCE Materia - Sophia. After trading, you can right-click your main character and choose "Return to Home World" to go back to the server.