Sending a heads-up to your guests a couple months before the actual date of your event is a nice detail that will make sure they’re available that day. This can be done by sending them a little card with a simple photo and the date of course or something as plane as sending them a text message. Again, with this task you can use your creativity on how you get the message to your guests. It doesn’t make a big difference on how you decide to tell them, as long as you do.
With the variety of guests there will be many different reasons for them to not be able to attend. Such as work, school, or other reasons. For example, if you have family visiting from out of town they have time to arrange a day or two off to attend your big celebration. This is something to keep in mind when your making your list of guests.