Curious 1000: Which means the difference between telling right before the engagement and telling a couple dates earlier is not that big a difference in time.
Midwest2: Those who date 10 or more times end up in Beis Din more often than those who get engaged after 5 dates. And those who date for half a year or more have an even higher divorce rate. Even 6-12 months of dating will often not reveal major faults.