modified Set Start and End Dates

validate_date_times.js

(function executeRule(current, previous /*null when async*/) {
	if (current.end_date < current.start_date) {
		gs.addErrorMessage('End date must be later than start date!');
		current.setAbortAction(true);
	}	
	var today = new GlideDateTime((new GlideDate().getValue()) + " 23:59:59");
	if(today.after(new GlideDateTime(current.start_date))) {
		gs.addErrorMessage('Start date must be after today');
		current.setAbortAction(true);
	}
})(current, previous);