Many couples are now performing was is commonly referred to as a “first look” in order to accomplish getting many of the group portraits out of the way. This enables them to get pictures while they’re still fresh, especially for outdoor summer weddings where you might get sweaty. It also enables them to eliminate some of the lost time between the ceremony and the reception where portraits would be taken, during cocktail hour.
There is a lot of “grip and grin” that you will be doing in order to greet all of your guests. If you are able to knock some of that out during cocktail hour, that means you will be able to enjoy more of your reception knowing that the obligatory greetings are out of the way.
If you are not going to see each other until the ceremony, be sure to leave a plentiful window of time between the ceremony’s estimated end time and the beginning of cocktail hour. This way you will not be stressed trying to fit an hour’s worth of family photo taking into 15 minutes. I do work very quickly, and having a specific order of operations (shot list) in hand helps.