konst37,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
$(".day-work").on("click", function (){
var dayMonth = $(this).parents(".panel-body").prev(".panel.panel-heading");
alert(dayMonth.data('day-month'));
});
});
</script>
</head>
<body>
<div class="panel panel-heading text-center" data-day-month="2017-06-01">День</div>
<div class="panel panel-body">
<div class ="row">
<div class ="col-sm-4 center-block">
<div class = "btn btn-default btn-sm day-work">Дневная</div>
...
</body>
</html>