Wording on save the dates

Help?!?! We live in Canada and are planning on getting married in Ireland in March 2019. I want to send out Save The Dates now and have guests RSVP to get the travel details once they are finalized. Having at least a ball park number of guests would greatly help when dealing with airlines for pricing and accommodations... i was planning on adding a card explaining this. That being said.... I'm not good with my words... Help me figure out how to say what needs to be said with out rambling.... via /r/weddingplanning http://ift.tt/2vd0eLA