We don’t have a lot of detail just yet, Cherabelle, but this is what they said so far in the News Article. Looks like it will become available starting October 27th.
As with character names today, desired names cannot be guaranteed. Early Name Reservation will be available from October 27 through November 3, 2026, for eligible upgrade purchases. During that window, names will be reserved on a first-come, first-served basis. If the full name you want is already taken or does not meet the naming requirements, you will need to choose another combination—or take a chance with the trusty in-game random name generator.