For all recent weddings (including ours) we got/sent a save the date email well in advance (months and months)...invites 8 weeks before - 8 weeks alone would not have been long enough for our O/S guests to save / plan / book .

Our wedding was in April - a busy wedding month so we wanted to make sure people knew when ours was. We have friends getting married in Sept and recieved the invite about a month ago and an email in January. Being UTD it was good to know what was coming up.