I would send them as soon as you get the wedding booked solid. That way you know that dates will not change, that the venues you want are open, ect, and you give them ample time to prepare for the trip.
We've been engaged over 2 years, and changed our plans multiple times. We finally set our date (11/21/09) and we booked the ceremony - so I just ordered our tropical themed "Save the date" magnets, and will be sending them out as soon as I finalize the guest list - which will hopefully be by this weekend.
That way, my family and friends have 9 months to look at that magnet and save up for our weekend wedding getaway and get excited for the trip!
they have a huge selection, and you can do a LOT of customizing! change colors, fonts, etc. They have magnet save the dates, both mini and larger, and they have paper cards too. I went with the 3.5x4 magnet. they are nice! my friend did the mini-magnet, and those are very nice too. good quality!
and, if they dont have a design you like, you can make your own. but, i think there is a $50 or $75 charge.
We are getting married in October 2010, and we will be mailing out the save the dates this week. Almost everyone is traveling at least 45 minutes...and as far as a 2 hour drive. It is also a holiday weekend. So, we want people to know as soon as possible so they can make arrangements.
So, I would send them as soon as you have the ceremony and reception places booked. I still have 19 months before mine, and will be sending them out now.
You can also even set up a hotel block and send hotel info with the save the date if you wanted to. I will be doing that since most people will be traveling too. It just gives them a heads up into the hotel and they can book sooner if they wanted to and dont have to wait for the invite.