Marriage and Family. Jewish marriages according to rabbinic sources show many formal similarities t the Greek and Roman practices. The marriage was a contract between families. It was effected in two stages: the betrothal (or "acquisition" of the bride) and the wedding proper (taking the bride into the husband's home). The betrothal had the legal force of marriage and could be broken only by divorce (cf. Matt. 1:18-19). It was accomplished by the bridegroom paying the bride-price (or part of it) or delivering a deed. The customary written contract (ketubah) included the husband's duties to his wife and the sum due her in the event of a divorce or his death. The bridegroom moving into his father-in-law's house to live with the bride without further ceremony was also recognized but discouraged in rabbinic writings. The wedding ceremony was held under a canopy (huppah). The bride was prepared by bathing, anointing, and clothing with special adornments. She was then escorted from her father's house to the accompaniment of song, dance, musical instruments, and (since usually in the evening) torchlight. The essential element of the wedding was the introduction of the bride into the groom's house, where the the huppah was set up. Seven blessings were pronounced on the couple and the marriage contract was read, followed by seven days of festivity.
I was probably thinking of the fact the betrothal, unlike our engagement, was a profound legal and financial committment, that required a divorce; but there is no warrant to say that the Virgin Mary shared St. Joseph's house.
Here is a possible reason why the Annunciation had to be close in time to the expected wedding:
I take it as axiomatic that the Holy Spirit so arranged the Incarnation that the virginal conception of the Christ would raise no doubts about Joseph’s paternity and Mary’s absolute fidelity to him in the minds of their families and neighbors. This is corroborated by the fact that even three decades later these same people were still unable to accept Jesus as being anyone but the son “of the carpenter” (cf. Matt. 13:55).There are therefore good grounds for holding that the Spirit must have so arranged the course of events that the angel Gabriel appeared to Mary no more than a few days before the date fixed for the completion of the nuptials, when Joseph would come in procession to her parental home and take her to his house, as this would have allowed virtually the full term to the Child’s birth to run its course after Mary had come to live under Joseph’s roof.
I also found this, by Pope John Paul II
We can wonder why she would accept betrothal, since she had the intention of remaining a virgin forever. Luke is aware of this difficulty, but merely notes the situation without offering any explanation. The fact that the Evangelist, while stressing Mary's intention of virginity, also presents her as Joseph's spouse, is a sign of the historical reliability of the two pieces of information.
[From: "The betrothal and marriage of Mary to Joseph" :] I take it as axiomatic that the Holy Spirit so arranged the Incarnation that the virginal conception of the Christ would raise no doubts about Joseph’s paternity and Mary’s absolute fidelity to him in the minds of their families and neighbors. This is corroborated by the fact that even three decades later these same people were still unable to accept Jesus as being anyone but the son “of the carpenter” (cf. Matt. 13:55).
This DIRECTLY contradicts the Protoevangelium of James:
[Chapter 11:] "1. Then came Annas the scribe, and said to Joseph, Why have we not seen you since your return? 2. And Joseph replied, Because I was weary after my journey and rested the first day. 3. But Annas turning about perceived the Virgin big with child. 4. And went away to the priest and told him, Joseph in whom you placed so much confidence, is guilty of a notorious crime, in that he has defiled the Virgin whom he received out of the temple of the Lord, and has privately married her, not revealing it to the children of Israel. 5. Then said the priest, Has Joseph done this? 6. Annas replied, If you send any of your servants, you will find that she is with child. 7. And the servants went, and found it as he said. 8. Upon this both she and Joseph were brought to their trial, and the priest said to her, Mary, what have you done? 9. Why have you debased your soul and forgotten your God, seeing you were brought up in the Holy of Holies, and received your food from the hands of angels, and heard their songs? 10. Why have you done this?"
So much for this guy's axioms. :) I'm not sure there is any way to know how long after the Annunciation that they were actually married.
However, the Protoevangelium clearly says that Mary was great with child BEFORE they were married. This is critical. Therefore, the Protoevangelium actually SUPPORTS my view that Mary was not expecting to actually BE married for some time, (it takes time to become great with child). So, Mary's question was logical. She was not expecting to be married any time soon, she would not dishonor her family by fooling around beforehand, and she was a virgin. How could it be that she would conceive a son? This is the basic and reasonable thought that prompted her question. (I thought it was interesting that under "Annunciation" at New Advent, they claim the two were already married at the time. Strange.)
[From Pope John Paul II:] We can wonder why she would accept betrothal, since she had the intention of remaining a virgin forever. Luke is aware of this difficulty, but merely notes the situation without offering any explanation. The fact that the Evangelist, while stressing Mary's intention of virginity, also presents her as Joseph's spouse, is a sign of the historical reliability of the two pieces of information.
What? How in the world does Luke "STRESS" Mary's intention of remaining a virgin. She asks how she can become pregnant since "I am a virgin". Does that, by itself, really translate into a lifelong pledge of virginity, especially from a betrothed woman? I can't see that at all, just on its face, never mind that Luke is stressing it.