Year over Year Report Question how to choose which month is first?
Caseを使って数式フィールドで並び替えたようです。
CASE( Month__c , 1, "11 -Jan", 2, "12 -Feb", 3, "01 -Mar", 4, "02 -Apr", 5, "03 -May", 6, "04 -Jun", 7, "05 -Jul", 8, "06 -Aug", 9, "07 -Sep", 10, "08 -Oct", 11, "09 -Nov", 12, "10 -Dec" ,NULL)