Paper, electronic or a combination (eg, paper invitation with website RSVP)?

Consider sending some form of save-the-date about 3 months prior to the event (particularly helpful for out-of-town guests)

If going the paper route, order printed invitations 6 months prior to event (and weigh out at post office to know how much postage will be required)

If sending paper invitations, mail to guests 6-8 weeks prior to event