How long does it take for a new database to get fork/follow and rollback capabilities?

Resolution

Before fork, follow, or rollback actions can be carried out against your database, Heroku's automated services must first complete a base backup of the database. On Heroku Postgres, base backups are capped around 10 MB/s to prevent performance degradation on the newly created database. You can roughly calculate the time it will take for fork, follow and rollback to become available by comparing the size of your database (available via heroku pg:info) against the 10 MB/s physical backup rate.