Открой шаблон и код в песочницу какую нибудь, наподобие codepen и ссылку сюда
[[*action_t_along:is=true:then=`
var actionDate = new Date(actionYear, actionMonth -1, actionDay+1); // счетчик зациклен
:else=
actionYear = [[*action_t_date:strtotime:date=%Y]],
actionMonth = [[*action_t_date:strtotime:date=%m]],
actionDay = [[*action_t_date:strtotime:date=%d]],
actionHours = [[*action_t_date:strtotime:date=%H]],
actionMinutes = [[*action_t_date:strtotime:date=%M]],
actionSeconds = [[*action_t_date:strtotime:date=%S]];
var actionDate = new Date(actionYear, actionMonth -1, actionDay, actionHours, actionMinutes, actionSeconds);
`]]
$('#countdown').countdown({
timestamp : actionDate
});