Long term capital gain tax

HI ,

My father has sold one land and got the money in installment .  Money I recieved in Nov 2014 . Registry done is 9th December 2014. 1) if I have to buy bond , I should buy within 6 months. How to calculate 6 month . is it from Registry date or from the date I recieved money in my capital gain account . Now all money is in capital gain account. Thanks rajesh