“According to the Bible, how long should a couple date before they get married?”
The Bible gives no specific time frame for dating before marriage, probably because dating (as we know it) was unheard of in those days. The Bible does offer some information about the process of getting married.
When Abraham arranged a marriage for Isaac, the courtship was brief. “Then Isaac brought her into his mother Sarah’s tent, and he took Rebecca, and she became his wife, and he loved her; thus Isaac was comforted after his mother’s death” (Genesis 24:67, New American Standard Bible).
Isaac had known Rebecca only a few minutes before marrying her. But the marriage arrangements and selecting the right mate for Isaac had been well-planned. This was the custom of the day.
In the story of Ruth and Boaz, we see a much more complex courtship. Space won’t allow all the details, but they came to know each other before making their commitment to be married. Only after becoming well acquainted did they marry, following the customs of that day.
The best information from the New Testament is the apostle Paul’s words to the unmarried. . .
“Now concerning the matters about which you wrote: “It is good for a man not to have sexual relations with a woman. But because of the temptation to sexual immorality, each man should have his own wife and each woman her own husband . . . But if they cannot exercise self-control, they should marry. For it is better to marry than to burn with passion.” (I Corinthians 7:1, 2, 9 – English Standard Version)
The apostle gives another insight into how long dating should take place. Once a couple becomes familiar and close, romantic and sexual feelings will naturally arise. So, Paul says, get married and enjoy the sexual relationship God intended for a husband and wife to have.
As to your question, some principles emerge. First, careful consideration should be given to the type of person you are dating. Is he or she the kind of person that will serve God and be compatible with you? Second, the customs of the day can be followed (such as legalities, ceremonies, etc). Third, a couple should not delay marriage so long that sexual temptations get the best of them.
As a practical timeline, I would suggest dating at least a year. This way you can experience and observe life events with your significant other. Carefully consider his or her interactions with family and friends. How are holidays, celebrations and tragedies dealt with? The ups and downs of everyday life? But remember, these suggestions are MY conclusions, since there is no clear command from God.