5:30 is becoming more common as more and more brides and grooms are opting to get married at the reception venue, rather than in a religious building. Since you don't have to incorporate the travel time between the wedding ceremony and the reception venue, they like to start the cocktail hour immediately following the service. The service is typically 30 minutes. So, based on a 5 hour reception, you either start at 5:30 and and the reception at 10:30 or you start at 5:30 and end at 11:00. We just went through this booking my daughter's wedding. They want to get married outside, overlooking the golf course, at the venue. I am thinking, though, that I will put 5:00 on the invitation. Weddings never start right on time. And I figure that if we get people there and seated and actually start at 5:15, we can manage another 15 minutes of mingling before the drinks are served . I can understand that. Tradition is important. There are some lovely dresses that are strapless and have matching "bolero" type tops for the service, that can come off for the reception. Daughter and I are planning to start looking Friday. So excited! Slightly off topic, had the engagement party on Sunday. 30 people at the house. 2 weeks of major cleaning, 3 days of cooking, I am exhausted! But, a great time was had by all .