jsは2つの時間が9ヶ月間違うかどうかを判断します.

function timeDifference(date1, date2){
		var newYear = date1.getFullYear();
		var newMonth =date1.getMonth() + 9;
		console.log(newMonth)
		if(newMonth >= 11){
			newYear += 1;
			newMonth -= 11;
			date1.setFullYear(newYear);
			date1.setMonth(newMonth-1);
		}
		else{
			date1.setFullYear(newYear);
			date1.setMonth(newMonth);
		}
		if(date1.getTime() >= date2.getTime()){
			return true;
		}
		else{
			return false;
		}
	}