Rule: trigger on the first day at 9 months later / 2 months earlier

9 month later  九ヶ月後

AND(

MONTH(DataOfferScheduledDate__c) <= 3 && TODAY() = DATE(YEAR(DataOfferScheduledDate__c), MONTH(DataOfferScheduledDate__c ) + 9, 1),

MONTH(DataOfferScheduledDate__c) > 3 && TODAY() = DATE(YEAR(DataOfferScheduledDate__c) + 1, MONTH(DataOfferScheduledDate__c) - 3, 1)
)

* Green number should sum up to 12

2 months earlier　二ヶ月前
AND(
MONTH(DataOfferScheduledDate__c) <= 2 && TODAY() = DATE(YEAR(DataOfferScheduledDate__c) - 1, MONTH(DataOfferScheduledDate__c ) + 10, 1),
MONTH(DataOfferScheduledDate__c) > 2 && TODAY() = DATE(YEAR(DataOfferScheduledDate__c), MONTH(DataOfferScheduledDate__c) - 2, 1)
)

* Change red number to any day you want