Order of The Theban Plays by Sophocles = Solve the mystery once for all.

"In the timeline of the plays, the events of Oedipus at Colonus occur after Oedipus the King and before Antigone; however, it was chronologically the last of Sophocles' three Theban plays to be written." Wiki

So here is the order of the story:
1. Oedipus the King
2. Oedipus at Colonus
3. Antigone

Now order of the writing:
1. Antigone
2. Oedipus The King
3. Oedipus at Colonus