calendar.on('beforeCreateSchedule', function(event) {
    var guide = event.guide;
    // Use guideEl$'s left, top to locate your schedule creation popup
    var guideEl$ = guide.guideElement ?
         guide.guideElement : guide.guideElements[Object.keys(guide.guideElements)[0]];

    // After that call this to hide the creation guide
    guide.clearGuideElement();
});