I actually found out how to fix this. I will use the MM/DD/YYYY format on the back-end but on the front-end, I will change the code to spit out the DD/MM/YYYY format. Very easy:
Change this (Plugins > Edit > RSVP > rsvp/rsvp_frontend.inc.php)
function rsvp_frontend_handler($text) {
global $wpdb;
$passcodeOptionEnabled = (rsvp_require_passcode()) ? true : false;
//QUIT if the replacement string doesn't exist
if (!strstr($text,RSVP_FRONTEND_TEXT_CHECK)) return $text;
// See if we should allow people to RSVP, etc...
$openDate = get_option(OPTION_OPENDATE);
$closeDate = get_option(OPTION_DEADLINE);
if((strtotime($openDate) !== false) && (strtotime($openDate) > time())) {
return rsvp_handle_output($text, sprintf(__(RSVP_START_PARA."I am sorry but the ability to RSVP for our wedding won't open till <strong>%s</strong>".RSVP_END_PARA, 'rsvp-plugin'), date("m/d/Y", strtotime($openDate))));
}
To This:
function rsvp_frontend_handler($text) {
global $wpdb;
$passcodeOptionEnabled = (rsvp_require_passcode()) ? true : false;
//QUIT if the replacement string doesn't exist
if (!strstr($text,RSVP_FRONTEND_TEXT_CHECK)) return $text;
// See if we should allow people to RSVP, etc...
$openDate = get_option(OPTION_OPENDATE);
$closeDate = get_option(OPTION_DEADLINE);
if((strtotime($openDate) !== false) && (strtotime($openDate) > time())) {
return rsvp_handle_output($text, sprintf(__(RSVP_START_PARA."I am sorry but the ability to RSVP for our wedding won't open till <strong>%s</strong>".RSVP_END_PARA, 'rsvp-plugin'), date("d/m/Y", strtotime($openDate))));
}