I got my invites out 2 days before the day I was planning on sending them. I was just too excited after MOH and I got them all stuffed that I had to run to the post office even though it's almost 9 at night.
We still have a few stragglers that I have to send invitations too, but my mother and grandfather will not give me the addresses of the people they want invited. (Seriously, it's not that difficult to get your friends addresses). So their friends will get their invites a little bit later, but hopefully I'll have those sent out within the week as well! It's only about 10 more invites, so it's not a big deal.