Great group photos start with getting everyone where they need to be quickly so there is plenty of time to get great, unhurried shots
As the wedding photographer doesn’t personally know everyone on each side of your family I recommend you assign a gatherer (enforcer) from each side of the family to corral everyone to the designated spot. This dramatically speeds up the process of getting great photos during the cocktail hour.
You want your wedding to be a big party and everyone to have fun, but guests want to party, particularly the guys who can get “ants in their pants” after the ceremony and head off to the bar. So I recommend you have the wedding coordinator (if you have one, or the “enforcer” if you don’t) make sure everyone has a drink as this will help take the edge off and lighten the mood. You want everyone to look like they are having the time of their life in your wedding photos
Have fun and get great pictures. You only get married once!