Probably not at all.
Also: Let me google that for you
Probably not at all.
Also: Let me google that for you
You're doomed.
Seriously, one workout is no big deal, unless you are the sort of person who has trouble with consistency. If you are, then you had better find a gym wherever the wedding is.
John Petrizzo trained on the morning of his wedding.
It will cause you to be 5 lbs behind what you would have been at had you trained.
In other words, it won't hurt your long term progress at all. Just pick it back up on Monday.