When did Paul's letters become "orthodox" or widely accepted as such in Christian communities?

My impression is that Christ cults were pretty diverse in the first two centuries following Jesus' death, including Jewish and non-Jewish variations, as well as Roman and Eastern, but if Paul became authoritative early on, then I would have to change my views on the scope of that diversity. It's obvious that once an ecclesiastical council determined that the letters officially belonged in the Bible, i.e, they were canonized, they became orthodox. But there's a lot of room between general and official acceptance.