[рони]

vladchv,

$(function() {
  var now = new Date,
      start = new Date(now.getFullYear(), now.getMonth(), now.getDate(), 19),
      end = new Date(now.getFullYear(), now.getMonth(), now.getDate()+1, 9);
  if (now >= start && now <= end) {
    if (localStorage.getItem("check") == null) {
      showModal();
    }
  }
  function showModal() {
    localStorage.setItem("check", true);
    $("#overlay").fadeIn(400, function() {
      $("#modal_form").css("display", "block").animate({opacity:1, top:"50%"}, 200);
    });
  }
  $("#modal_close, #overlay").click(function() {
    $("#modal_form").animate({opacity:0, top:"45%"}, 200, function() {
      $(this).css("display", "none");
      $("#overlay").fadeOut(400);
    });
  });
});