Read closely Rev 1:9
9I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ.
Note the word highlighted, "was", that it's past tense. Why past tense and not present tense? If John were writing while yet on Patmos, "was" would not have been used, but rather 'am'. This leads me to believe it was written sometime after his exile had ended, consistent with Rev 10:11 wherein he's told he must again prophesy (below).
Rev 10:11
11And he said unto me, Thou must prophesy again before many peoples, and nations, and tongues, and kings.
9I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ.
Note the word highlighted, "was", that it's past tense. Why past tense and not present tense? If John were writing while yet on Patmos, "was" would not have been used, but rather 'am'. This leads me to believe it was written sometime after his exile had ended, consistent with Rev 10:11 wherein he's told he must again prophesy (below).
Rev 10:11
11And he said unto me, Thou must prophesy again before many peoples, and nations, and tongues, and kings.