From the Ascension of Isaiah chapter 11:
3. And he came into his lot. And when she was espoused, she was found with child, and Joseph the carpenter was desirous to put her away.
4. But the angel of the Spirit appeared in this world, and after that Joseph did not put her away, but kept Mary and did not reveal this matter to any one.
5. And he did not approach May, but kept her as a holy virgin, though with child.
6. And he did not live with her for two months.
7. And after two months of days while Joseph was in his house, and Mary his wife, but both alone.
8. It came to pass that when they were alone that Mary straight-way looked with her eyes and saw a small babe, and she was astonished.
9. And after she had been astonished, her womb was found as formerly before she had conceived.
10. And when her husband Joseph said unto her: "What has astonished thee?" his eyes were opened and he saw the infant and praised God, because into his portion God had come.
11. And a voice came to them: "Tell this vision to no one."
12. And the story regarding the infant was noised broad in Bethlehem.
13. Some said: "The Virgin Mary hath borne a child, before she was married two months."
14. And many said: "She has not borne a child, nor has a midwife gone up (to her), nor have we heard the cries of (labour) pains." And they were all blinded respecting Him and they all knew regarding Him, though they knew not whence He was. (
http://www.earlychristianwritings.co...ascension.html)
This apochriphal text is probably the only source about the birth of Jesus that is indipendent from the Gospels - very older than the ProtoGospel of James.
The chapters 6-11 date on about the 70ad for some scolars, according others (more probable) they date about the 120ad, surely before the 135ad.