When did St. Andrew become a saint?

Saint Andrew died a martyr's death by being crucified on an x-shaped cross. In the early years of the church there was no official canonization process. That did not occur until the 12th century. Andrew would have been proclaimed a saint by the early Christians who knew him well and, perhaps, witnessed his martyrdom. When a person suffered martyrdom for their faith, they were almost automatically assumed to be a saint.