How to make jquery count down timer function manually editable

I have a wordpress theme and I would like to display a certain promo start time in front page. It uses jquery.countdown.min.js and has following default timer settings

var siteCountDown = function() {          if ( $  ('#date-countdown').length > 0 ) {             $  ('#date-countdown').countdown('2020/10/10', function(event) {               var $  this = $  (this).html(event.strftime(''                 + '<span class="countdown-block"><span class="label">%w</span> weeks </span>'                 + '<span class="countdown-block"><span class="label">%d</span> days </span>'                 + '<span class="countdown-block"><span class="label">%H</span> hr </span>'                 + '<span class="countdown-block"><span class="label">%M</span> min </span>'                 + '<span class="countdown-block"><span class="label">%S</span> sec</span>'));             });         }      };     siteCountDown(); 

It displays that promo will start in four months later after now. But I would like to set timer manually via wordpress admin dashboard. Is it possible to insert some php codes in .countdown(‘2020/10/10’ something like

<?php if ($  year = get_option('of_year') && $  month = get_option('of_month') &&  $  day = get_option('of_day') ) { ?> .countdown('<?php echo $  year; ?>/<?php echo $  month; ?>/<?php echo $  day; ?> <?php }  ?> 

so that I can edit promo start time manually

My options are:

$  options[] = array( "name" => "Year",                     "desc" => "promo start year",                     "id" => $  shortname."_promo_year",                     "std" => "",                     "type" => "tex");   $  options[] = array( "name" => "Mount",                     "desc" => "promo start month",                     "id" => $  shortname."_promo_month",                     "std" => "",                     "type" => "tex");  $  options[] = array( "name" => "Day",                     "desc" => "promo start day",                     "id" => $  shortname."_promo_day",                     "std" => "",                     "type" => "tex");