Almost every wedding I have been to started late. Some guests arrive early to get a good seat then you add that to a late start and you have guests waiting for almost an hour in silence. Sometimes it's an outdoor wedding and the guests were all dressed up with sweat soaking up their beautiful gowns and suits.
I don't have any tricks to getting a wedding started on time but I do have a tip to calm the savage beasts. When you hire a wedding musician, have them start about 20 minutes before the wedding performing some calming music for the guests. That way they will enjoy their wait and feel the event has started on time because the music is part of the event.
The guests will have a much more favorable recollection of a tardy event if they have some entertainment while they arrive. It makes for a smooth transition into the wedding ceremony. Good luck.