Our wedding is in October of next year. I got the preliminary invitations and save the dates today (I designed them myself using an art program and wanted to make sure they'd print correctly) and I love them. We're planning to send out Save-the-Dates by the end of January as it is 3-4 hours for pretty much everyone. Due to various reasons, we wound up going with a smaller venue.
I've been told for anything that requires guests to travel a fair distance, invitations should be sent out as much as 10 months in advance. We have more than our venue can hold (Capacity is 96, our guest list currently has 160 with others that we want to add if at all possible) so we need to stagger invitations which we have basically divided into three groups. Some of those people have told us there's only a small chance they'll able to make it (about 20-30) but wanted to receive Save the Dates and Invitations anyway, so the first group is the biggest group to go out (About 60% of the list).
This is our plan at this time:
January 31st - Send out Save the Dates
March 1st - Send out group 1 of invitations
April 30th - Cutoff For group 1 to have received their invite and RSVP
May 1st - Send out group 2 of invitations
June 31st - Cut off RSVP for group 2 of invitations
And in July if we aren't full, we would send the last round of invitations to group 3.
With the way that the venue is setup we have devised a way to have some extra seating that won't count against capacity, but it won't be a ton (maybe 10-20 people at most).....and we've gone over the list like 30 times and can't figure out anyone else to take off the list.