Registration of Gift Deed

Hi, My father (who is a NRI who purchased Agricultural land way back in 1989) wants to gift it to me before becoming a Resident Indian. He had purchased the agricultural land in 1989 when he was still a NRI but wasn't told by his lawyer that as NRI you can't purchases. So he did it. Now he wants to gift it to me (I am a Resident Indian) so as to avoid hassles later on. Our question is, since when is the gift valid: 1) From the date on the gift deed? 2) From the date the stamp duty is paid on value of gifted land? 3) From the date the gift deed is registered? 4) Is there any other registration that is to be done to ensure that the land is now mine? And if so, is this the dat gift is effective? Please let me know. Also, if we make a gift deed, I understand we need to pay stamp duty. But after paying stamp duty, is there a time limit within which registration must be done? Please let me know. And thank you in advance for taking time to read and answer my query.