Weddingbee boards

I suggest giving a buffer. 

How long of a buffer depends on a lot of things... 

1-is your ceremony @ a house of worship that will require a specific start time? 

2-is your ceremony venue local to most of your guests?

3-are the majority of your guests punctual people?

4-physical location aspects - i.e. is there a possibility of inclement weather that might hamper people's ability to get to your site?  is your site in a large city where there might be rush hour/gridlock?

Personally, our scheduled ceremony start time is 7pm, but we put 6:30pm on the invites because:

a. our wedding is in January in NYC on a Friday night - weather and traffic to account for.
b. our friends and family are notoriously not punctual.
c. we want to give people ample time to check their coats and warm up! 

Luckily for us, we're doing our ceremony @ the same place as our reception, so when guests arrive, they'll be served mini hot chocolates and sparkling water at the bar until everyone arrives & is seated for the ceremony.