We put all the details on how to book with our TA and about the deposit on our wedding website and then included the wedding website on our save the date cards. Also, as I was worried that some people might not go to the website (or have internet access!) we included a "Travel Information" letter with the Save the Date card that explained everything, and had the following notation: "NOTE: Air Canada requires a deposit of $150 per person at the time of booking to hold the vacation package. Should you choose to use the group rate, this is due no later than October 2, 2011. Because there is an Early Booking Bonus in effect, all packages have to be paid in full by Jan 6th 2012. You can make your final payment at any time prior to Jan 6th ..."