This whole dating thing is insane.  How did it ever become normalized?  It’s despicable that parents allow their daughters to run off and have flings with young men.  Total delinquency of duty.  They’ve destroyed several generations of young people through their “tolerance” of change.  Men need to step up and lay the law down in their households.  It is not up to mothers to decide what goes and what doesn’t.  Men have the clear sight to recognize threats and STOP them before anything happens.  Women have all the charity to welcome people and make them feel at home.  They do not have the sense to make reasonable ground rules.  Men should never have allowed this to happen.  All of the world’s problems can be attributed to effeminate men.

Having gone through this with two of our older children, courtship shouldn't last too long.  Courtship is designed to determine if someone is marriage worthy or not.  It's definitely not dating, in the modern sense.  If a man or woman can't determine the marriage worthiness of someone in 6 months or less, then it's time to move on.  6 months should give a couple plenty of chaperoned time together and meet the families in order to make a determination.  

Of course, that's just my opinion.  

I would say a year to 18 months, some could do it in less, especially if they or their families have known each other for quite some time.  There is much to be said in favor of marrying one's "childhood sweetheart".