First CONGRATS!!!
And yes 'our kind of people' do it too. My friend had an elegant wedding horse and carriage and everything over 100 people and the week of people were still RSVPing and she sent the invites. 3-4 months in advance! I was the Maid of Honor and I made calls to double check on some folks since I was calling about the gifts from the bridal party (there were 20 of us) and the events for the night before.. so that's an idea!